I know the guys will roll their eyes, but I thought the ladies present might like this one.
CmdSmg at SMGFAN has compiled a list of all the fashions Sarah has worn in her appearances and it's impressive work.
Thanks CmdSmg!! 
AWARDS SHOWS:
1995 22nd Annual Daytime Emmy Awards: Vera Wang Dress
1998 50th Annual Emmy Awards: Chloe Bustier corset and Ralph Lauren floor legnth skirt
1999 71st Academy Awards - Elton John/Vanity Fair Party: Haulsten dress
1999 51st Annual Emmy Awards: Vera Wang dress and Jimmy Choo Heels
2000 Teen Choice Awards: BCBG Max Azria dress, Chloe sunglasses and Jimmy Choo heels
2001 58th Annual Golden Globe Awards: Valentino dress and Jimmy Choo heels
2001 Teen Choice Awards: Seven For All Mankind Jeans, Fendi bag and Fendi Sunglasses
2002 Nickelodeon's 15th Annual Kids Choice Awards: Seven For All Mankind Jeans and Gucci heels
2002 Movieline's 4th Annual Young Hollywood Awards: Roberto Cavalli dress and Gucci heels
2002 Teen Choice Awards: Seven For All Mankind Pants and Cathy Waterman necklace
2002 13th Annual Glamour Magazine's Women of the Year Awards: Vera Wang dress and scarf and Manolo Blahnik heels
2003 Teen Choice Awards: Foley And Corrona top, Paper, Denim and Cloth Jeans, Louis Vuitton bag, Marie Chavaz earrings and Gucci Geels
2003 14th Annual GLAMOUR Women of the Year Awards: Vera Wang top
Divine Design 2003 Gala Honors Sarah Michelle Gellar and Louis Vuitton: Prada dress
2004 Hollywood Reporter's 33rd Annual Key Art Awards: Dior bag and flats
2004 4th Annual Taurus World Stunt Awards: BCBG Max Azria dress
2004 15th Annual GLAMOUR Women of the Year Awards: Collette Dinnigan dress and Neil Lane earrings/bracelets
2004 MTV European Music Awards: Vera Wang dress (On stage; cremeish)/ Ungaro dress and Bvlgari jewelry (Whie one; Arriving and on stage)/ Collette Dinnigan dress and Bvlgari jewelry(Blue one on stage)/ Collette Dinnigan top, Citizen of Humanity Jeans and Jimmy Choo heels (After EMA's; press room)
2005 CFDA Fashion Awards: BCBG Max Azria haute couture dress
AOL In2TV Influencer Awards: Rebecca Taylor dress and Jimmy Choo heels
2007 Academy Awards -15th Annual Elton John AIDS Foundation Oscar Party/Vanity Fair Party: Jay Godfrey dress, Gunmetal clutch, Bochic jewelry, and Jimmy Choo heels
MOVIE PREMIERES:
"Moulin Rouge" Australia Premiere: Collette Dinnigan dress and Jimmy Choo heels
"Summer Catch" Premiere: Chloe pants and Jimmy Choo heels
"Scooby-Doo" Premiere: Madelin Akerberg top/skirt and Fendi bag
"Bringing Down the House" Premiere: Seven For All Mankind Jeans
"Scooby-Doo 2" LA Premiere: Jimmy Choo Heels and Nathan and Mo earrings
"Scooby-Doo 2" UK Photocall: Collette Dinnigan dress and shoes
"Scooby-Doo 2: Monsters Unleashed" London Premiere: Collette Dinnigan dress and shoes
"Spider-Man 2" Premiere: Stella McCartney top, scarf and pants, Jimmy Choo heels and Marie Chavaz earrlings
"The Grudge" Los Angeles Premiere: Jennifer Nicholson dress and Givonchy heels
2004 Dubai Film Festival: Prada Dress and Jimmy Choo heels
"The Grudge" Italy Premiere: Vera Wang top and Jimmy Choo heels
"The Grudge" Paris Photocall: Chloe top and Jimmy Choo heels
"The Grudge" Paris Premiere: Vera Wang top and Jimmy choo heels
"The Grudge" Tokyo Press Conference: Moschino dress and Manolo Blahnik heels
"The Grudge" Japan Premiere: Moschino dress and Jimmy Choo heels
"The Grudge" Amsterdam Premiere: Juicy Couture Jeans
"Southland Tales" Premiere/Screening at Cannes: Vera Wang couture gown and heels
"The Grudge 2" California Premiere: Jenny Packham dress and Christian Louboutin heels
"Suburban Girl" Tribecca Film Festival Premiere: Chloe dress and Jimmy Choo heels
"The Air I Breath" Tribecca Film Festival Premiere: Donna Karen dress, Chanel jewelry, and Jimmy Choo heels
"The Air I Breath" Tribecca Film Festival After Party: I believe she is wearing a Marchesa dress-- heels are Christian Louboutin and both clutch and jewelry is Chanel
"Hairspray" UK World Premiere: Amanda Wakeley dress, Christian Louboutin heels, and a Chanel clutch
AFI FEST 2007 Presented By Audi Screening Of "Southland Tales: VINTAGE Chloe dress (skirt converted into a dress by Sarah Michelle and her stylist), Fendi oversized clutch, Lanvin necklace, Christian Louboutin heels, and 14 Karets stacked bengles
Premiere of "The Air I Breathe"- Temperly dress, BoChicjewelry, and Jimmy Choo heels
TV:
Buffy Meets Blackwood: Burberry handbag
The Cast of "Scooby Doo" on TRL: Seven For All Mankind Jeans and Gucci heels
Late Night With Conan O'Brien 2002: Seven For All Mankind Jeans and Gucci heels
Access Hollywood September 2004 (On set for Entertainment Weekly shoot): Intuition cream wrap top
The Ellen Degeneres Show 2004: Marie Chavaz earrings and Juicy Couture jeans
Late Night with Conan O'Brien 2004: Dolce and Gabbana Dress
David Letterman 2002: Vera Wang dress and Jimmy Choo heels/ Seven For All Mankind Jeans, American Couture NYC GIRL top and Adidas sneekers
Live With Regis & Kelly 2004: Vera Wang skirt and Christian Louboutin heels
The Tony Danza Show 2004: Marie Chavaz necklace
David Letterman 2004: Stuart Weiztman heels
MTV TRL (Grudge 2 Promotion): Chloe top and boots, J Brand jeans, Lorraine Schwartz necklace, and outside of TRL she was toting her PRADA bag that she was also using @ the Rebecca Taylor fashion show
Live with Regis and Kelly 2006 (Grudge 2 Promotion):Christopher Deane top, J Brand jeans and Moschino boots
Late Night with Conan O'Brian: Lorraine Schwartz necklace (working on the dress...gimmie time, lol)
This Morning UK appearance: Chloe dress, Christian Louboutin heels, and later she was sporting Dior shades and a Lanvin bag
David Letterman 2008: Herve Leger dress, Chanel coat, and Christian Louboutin heels
OTHER:
2001 UPN Summer Press Tour: Valentino halter top and Louis Vuitton bag
UPN Prime Time 2002-2003 Upfront Party: Fendi bag and Gucci heels
Scooby Doo Press Conference: Frankie B pants
2003 Mercedes-Benz Fashion Week BCBG Spring 2004: BCBG top, pants, shoes and Marie Chavaz earrings
2003 Mercedes-Benz Fashion Week Tommy Hillfiger Spring 2004: Tommy Hillfiger Jacket and Pegah Anvarian top
2003 The Young Survival Coalition's 5th Anniversary Celebration: Richard Tyler dress
Entertainment Weekly's Celebration of "The Must List": Stella McCartney top and skirt and Gucci heels
2005 ABC Upfronts: Giuseppe Zanotti heels
Silver Spoon Hollywood Buffet: Dior Sunglasses
Max Azaria Collection Resort 2005: Diane Von Furstenbergdress and BCBG shoes and caplet/jacket
Opening of the New BCBG Max Azria Flagship Store in Beverly Hills: BCBG Max Azria dress and shoes, Neil Lane jewelry and Lauren Mirkin bag
InStyle Magazine Summer Soiree: BCBG dress, Neil Lane jewelry, Lauren Mirkin bag and Manolo Blahnik heels
DKNY JEANS Presents VANITY FAIR In Concert: Vera Wang dress, Neil Lane jewelry, Lauren Mirkin bag and Jimmy Choo heels
Natalia Livingston's Birthday party : Kooba bag and Me&Ro earrings
"Southland Tales" Cannes Photocall/Press Screening: Vera Wang heels and Vera Wang Dress
Chopard Trophy Awards - Cannes 2006: Marchesa gown and Vera Wang heels
Olympus Fashion Week Spring 2007-Max Azria Spring 2007: Dress, Clutch (bag), and Jacket all Max Azria .Prada Heels and Chanel black nail-polish.
Olympus Fashion Week Spring 2007-Marchesa Spring 2007 Fashion Show: Marchesa dress, Prada heels, Chanel black nail polish, and I'm working on her bag...
Olympus Fashion Week Spring 2007-Marie Claire Hosts "Haute Shopping Soho" with Sarah Michelle Gellar: Marchesa dress, Prada heels, and Chanel black nail polish.
Olympus Fashion Week Spring 2007-Victoria's Secret Pink Hosts The Phi Beta Pink Party: Prada heels and Chanel black nail polish, again, still working on that bag...
Olympus Fashion Week Spring 2007-Vera Wang show at the Spring Collections 2007, Manolo Blahnik Makes A Personal Appearance At Bergdorf Goodman, and W VIP Lounge At Olympus Fashion Week (3 events, same day, one after another): Vera Wang dress, Christian Louboutin ankle boots and Chanel black nail polish. She also tried on a pair of Mr.Blahnik's heels at his signing.
Olympus Fashion Week Spring 2007- Rebecca Taylor Spring 2007 Fashion Show:Rebecca Taylor sweater wrap, BCBG top, Marie Chavez neclace, Tsubi skinny jeans, Chanel black nail polish, PRADA bag (@ her feet- barely visible) and brown PRADA mary-jane heels
Sarah Michelle Gellar and Baume & Mercier Hosts The Launch Of Club Phi and preview of Fall 2006 collection: Top and skirt PRADA, BCBG heels, Chanel black nail polish, Mimi So Jewlery, and Baume & Mercier watch
Chanel Dinner At The 2007 Tribeca Film Festival: Chanel dress, jewelry, heels and clutch
2007/8 Chanel Cruise Show Presented By Karl Lagerfeld: Chanel dress, heels, jewelry, and clutch.
Moca Summer Party and Silent Auction: Christian Louboutin heels, Chanel bag, and Hermes cuff bengle
The Fifth Annual Art Party Celebrating The Whitney Museum Of American: Max Azria dress, Christian Loboutin heels, and Van Cleefe & Arples jewelry
Harrods Summer Sale kickoff: Jasmine Di Milo satin romper one-piece, Christian Louboutin heels, and Marni coat
InStyle Magazine Summer Soiree: Notte By Marchesa dress, Stacey Lapidus bengles and Christian Louboutin heels
"Une Journée À Paris" Hosted by Van Cleef & Arpels: Chanel dress and clutch, Christian Louboutin heels, and Van Cleef & Arpels jewelry
Mercedes-Benz Fashion Week Spring 2008- Ports 1961: Ports 1961 dress and shoes. Stacey Lapidus bengles.
Mercedes-Benz Fashion Week Spring 2008 - Vera Wang- Vera Wang dress and Christian Louboutin heels.
Chanel and P.S. Arts Event- Chanel dress, clutch, and jewelry. Christian Louboutin heels.
Us Weekly's Hot Hollywood- Chloe dress, Christian Louboutin heels,Devi Kroellclutch, and Chanel black nail polish (!!!)
Cocktail Reception Honoring Sarah Michelle Gellar, CARE Ambassador and SELF Magazine October 2007 Cover Model- Alberta Feretti dress, Christian Louboutin heels, Tito ring, Chanel clutch, and a "Care" necklace by Helen Ficalora (Get yours and Donate!
http://www.helenficalora.com/pg_Care.asp)
Lucky Magazine's Lucky Shops V.I.P. Preview Party- Dolce and Gabanna dress and Christian Louboutin heels
Juicy Couture LA Store Opening: Juicy Couture skirt and top, Christian Loboutin heels
Southland Tales Press Junket: Ports 1961 dress and Chanel necklace and cuff
Allure Coctail party: Chloe coat, Christian Louboutin ankle boots, Wolford tights, and a Chanel bag
SARAH & FREDDIE'S WEDDING:
Sarah's gown and heels: Vera Wang
Sarah's dress after wedding: BCBG Max Azria
Freddie's white linin suit: Sy Devor
Sarah's bridesmaids: All dress' and heels Vera Wang
Freddie's groomsman: All suites Sy Devor
Sarah & Freddie's platinum wedding bands: Cathy Waterman