Although I wouldn't reccomend buying them, (as it might not be your thing), anime's you should watch are:
-Baccano
-To Love Ru
-Akikan
-Hayate The Combat Butler, (has loads of refernces, and is very funny at times, but is over the 50 episode limit, but awesome none-the-less)
-Shakagan No Shana, (just under 50 episodes! XD)
Needless has already been suggested, but I also agree that this is a very good series to watch.
As for old classics, (that span over 50 episodes, but you can always watch them online), I would also reccomend Tenchi Muyo, and Ranma, (which has a ridiculous no. of episodes, and I've only seen like 15 or so, but its very good stuff, and its obvious a lot of modern animes are inspired by it).