I was wondering if there are any vampire clans in the game.

Nope. The closest you get is the farcical labeling of the strongest leveled vampires as "Volkihar."

Are there any quests only vampires can get in this game? Seems kind of lame how Werewolves get all the love and Vampires get nothing.

I never though of it till now but thats a good mod idea. A vampire Guild/Clan/Nest. It would give people a reason to try the Fangs on. I tried vamp in oblivion and it was cool for a bit but got old because everyone hated me, i wish i had vamp friends.....

Speaking of mods, isn't the Creation kit supposed to be available soon or something? What or how much does that do for modding?

Not that I recall, no. I recommend checking the wiki, though, because I was too disgusted with vampirism to bother retaining it long enough to find out.

Vampirism definitely needs a large overhaul in this game. And Werebears need to be added in the game, since TES lore states that the Werebear is the most common variety of lycanthrope in Skyrim, and yet there is not a single one to be seen in the game.

lol I think werebears should have special abilities. And the abilities should be displayed by a symbol located on their stomache perhaps?