I'm currently really enjoying the DC animated universe. I've been watching Superman. I've previously enjoyed the JLA/JLU and of course Batman (pre robin). I'm watching the Green Lantern cartoon (presumbly by the clone wars guys) and enjoying that too. What else is around? I'm not so much interested in the movies, more the series. Has Marvel got anything of note?
Avengers: Earth Mightiest Heroes is very good. Although it mucked with cannon (less than Ultimate Spider-Man) I really enjoyed Spectacular Spider-Man as well.
You may also want to get the Batman/Superman movies (Crisis of Two Worlds, Superman Vs the Elite, and so on.)
I really enjoyed the shorts in the Superman/Shazam! collection of short films (the Spectre, Green Arrow, and Shazam ones were very nice.)
the Brave and the Bold is actually really awesome. Ok it's a kids show and it's lighter in tone (than the other dc cartoon kid shows of course), but it's witty and there's a real appeal for dc continuity fans/silver age fans.