How come no one mentioned Kanamemo yet ? It's one of the newest shows, though I'm not too sure of the nature of the show
Comedy ? Drama ? Yuri ? Or Yuri fanservice ? Not too sure. There's plenty of comedy yes, so even if not for the yuri, it's a good watch.
Then there's Aio Hana ( already mentioned ), and Girl Friends ( manga ). Girl Friends is the best yuri manga I have ever read so far. Highly recommended.