If you liked
Makai Senki Disgaea
|
...then you might like
Dororon Enma-kun Meeramera
|
Similar themes and archtypes but different settings. Both main characters are demon princes with scantily glad sidekicks. Enma-kun is a dirty minded Earth based cousin of Disgaea with more references. I think if you like one you'll like the other
If you liked
Genshiken
|
...then you might like
Heppoko Jikken Animation Excel♥Saga
|
While completely different in both storyline, setting, pace, style and pretty much every other way, the thing that links them both is their great many references to other animes. An otakus dream really, see how many references and spoofs of your other favourite anime you can find!
If you liked
Ai yori Aoshi
|
...then you might like
AI ga Tomaranai!
|
These struck me as pretty similar when reading. Of course them both being typical boys fare (harem style) is obvious but they also have the main characters pair up at the start and be actually content together. It's all the other girls that are the problem. Both also have similar American characters.