Originally Posted by levite

I second many of those already posted, like Michelle Trachtenberg, Monica Bellucci, Salma Hayek, Jennifer Connelly, Allyson Hannigan, Jeri Ryan, Scarlett Johanssen, and others.

Haven't seen mentioned yet that need mentioning:

Kate Winslet
Summer Glau (from Firefly/Serenity, Terminator: Sarah Connor Chronicles)
Kandyse McClure (from Battlstar Galactica-- the SciFi series, not the original)
Mila Kunis (That 70s show)
Rhona Mitra (guested on Nip/Tuck, The Practice, Boston Legal, Gideon's Crossing, Party of Five, other small roles)
Julia Stiles (The Bourne movies, 10 Things I Hate About You, Save The Last Dance)
Rachel Weisz (The movies with Brendan Fraser)
Hayden Panettiere (Heroes)