So I know of a few-
Quizilla.com,
Fictionpress.com,
and Fictioncentral.net ((although I really dislike that one. =/))
Does anyone know of any other good writing sites?

There's always just writing.com =)

Really, its a website

Yeah...not my favorite, though. =/
DeviantArt is supposed to be pretty good;;
anyone tried it yet?

well there's always fanfiction.net. also, Urbis.com is pretty cool, but you have to be willing to review other writing--that is if you want to read the reviews on your own writing. i personally dislike most online writing sites just because i can never find decent writing. all the good stuff (and even a lot of the not so great stuff) is already published. oh, another site for just reading stuff is wordshack.com. you have to pay to be published there, though.

^ I use Fanfiction as well. DeviantArt I've never tried. But you get a lot of reviews for FanFiction if its good.

i like deviantART... i love it! :)