Well, I don't think I've ever seen her in anything...
I mean, I can definitely understand that response for a good chunk of the girls posted in these threads (I haven't seen loads of them in anything either), but Marisa Tomei has been moderately high-profile for more than two decades, been in a lot of different movies spanning many different genres, won an Oscar and been nominated for others, has been interviewed zillions of time... you must surely have seen her in something!
Well, I know who she is, because she's famous, but, in looking over her IMDB listing, it seems the only things I could possibly have seen her in were Toxic Avenger
and Rescue Me
, if she happened to be in one of the two episodes I suffered through. But I don't really remember.