A great list from EW.com, courtesy of our pal Bev. All the usual suspects are here (Fey, Silverman, Poehler, Louis-Dreyfus) so I included some that a bit more off the radar.
JANE LYNCH

AGE: 48
CATCH HER IN: Julie & Julia this summer
SCHTICK: Straight-shooter persona belied by truly transgressive humor (see: oh-she-went-there turns in Role Models, The 40 Year-Old Virgin).
KRISTEN WIIG

AGE: 35
CATCH HER IN: Saturday Night Live
SCHTICK: Spot-on, scarily diverse impersonations (Kathie Lee Gifford, Suze Orman, Björk); perfect timing (see: Knocked Up); crucial absence of onscreen vanity.
JANE KRAKOWSKI

AGE: 40
CATCH HER IN: 30 Rock
SCHTICK: Turns self-absorption into an art form; finds inappropriate moments to showcase Broadway-baby song-and-dance skills; glorious hair.
OCTAVIA SPENCER

AGE: 36
CATCH HER IN: Bad Santa, Ugly Betty; this summer's horror flick, Drag Me to Hell
SCHTICK: Sassy, smart and wise beyond her years; she's at home in either comedy or drama — Spencer's been a staple of the TV drama guest-star pool for more than a decade, appearing on CSI: NY, NYPD Blue, and Medium.
ARI GRAYNOR

AGE: 25
CATCH HER IN: Nick & Norah's Infinite Playlist, Drew Barrymore's upcoming roller derby pic, Whip It
SCHTICK: Ditzy-smart charisma; no fear of bodily harm; willingness to get up close and personal with public toilets (see: Nick & Norah).
WANDA SYKES

AGE: 45
CATCH HER IN: The New Adventures of Old Christine
SCHTICK: Turns sidekick roles into spotlight-stealers (see: Monster-in-Law, Curb Your Enthusiasm); acerbic wit; bone-dry delivery.
EMILY BLUNT

AGE: 26
CATCH HER IN: The Devil Wears Prada, Charlie Wilson's War, Sunshine Cleaning
SCHTICK: Turns neurotic, posh-accented haughtiness laced with a formidable caustic wit into comedy gold; hilarious deftness at tackling no-nos like eating disorders. (See: ''I'm one stomach flu away from my ideal weight!'' in The Devil Wears Prada) Also: very sexy. Exhibit A: her striptease in Charlie Wilson's War.
ALLISON JANNEY

AGE: 49
CATCH HER IN: The West Wing, Juno, this year's Away We Go
SCHTICK: Versatility. Janney can play any kind of funny — brainy, trashy, oddball maternal — with a combination of energetic wit, physical comedy, and legitimate emotional depth.
KRISTEN SCHAAL

AGE: 31
CATCH HER IN: Flight of the Conchords, her own upcoming Comedy Central special
SCHTICK: Baby-faced badass. Schaal's wide eyes and lisp-inflected delivery make her a hilarious stalker — and an unconventional (and uniquely silly) voice for pop feminism.
EMMA STONE

AGE: 20
CATCH HER IN: Superbad, The Rocker, House Bunny
SCHTICK: Stone has proved herself the perfect comedic foil for boisterous co-stars like Jonah Hill, Rainn Wilson and Anna Faris. Plus, she appeared in the 2004 Vh1 reality talent competition, In Search of the New Partridge Family. And with that on her résumé, we have to imagine she has one helluva sense of humor.
NICOLE SULLIVAN

AGE: 39
CATCH HER IN: MadTV, King of Queens, Rita Rocks
SCHTICK: Goofy faces and killer impressions. Really, was there any MadTV cast member funnier than Sullivan, the pixie-ish comedienne who rose to notoriety with silly characters like the Vancôme Lady? We say, ''Cha, you know what? Uh-uh!''
MAYA RUDOLPH

AGE: 36
CATCH HER IN: Saturday Night Live, A Prairie Home Companion, this summer's dramedy Away We Go
SCHTICK: Uncanny ability to channel the tanorexic megalomania of Donatella Versace (''Get Ouuuuuuut!''); makes excellent comedic use of her impressive singing voice (see: her Beyoncé on SNL's ''The Prince Show''); astonishing chameleon-like power to impersonate everyone from Michelle Obama to Paris Hilton.
See the rest here at EW.com.