http://www.deviantart.com/ <-- You've had to of heard of this one by now. It's not totaly furries but there are quite a few on there (like TONS) you can also sign up and it's free (unless you want to pay for a subscription you get some benifits but meh I like my free account) you can also post your own art and watch other people. Which is pretty sweet, every time a person you watches posts something you get a little annousment on the top of the page. Oh if you already have an account there tell me so I can stalk you.
http://sheezyart.com/ Not quite as well known, but still quite a few furry artist there. Like Deviant Art just in a different place.
http://www.furaffinity.net/ I currently don't have an account there, but it's basicly all furry art all the time.
http://us.vclart.net/vcl/ WARNING NOT MENT FOR YOUNG VIEWERS! Good furry art but half the time you have to wade through tons of adultish furry art. But if it's furry it's there. I don't recomend it for younger viewers due to the amount of nakidness and fetish type art there. Even I tend to stick to just the thumb nails, I have been disturbed a few times.
http://www.ozfoxes.com/fauxpas.htm Not anthro, but it is about animals, very cute comic ^-^
http://www.oohbitey.com/ Nothing to do with furry art, just a very fun place with lots of funny flash movies. I've gotten such a kick outa half of thoes. I even have the front art as my desktop BG