Batman:TAS along with all the followups, Superman TAS, Justice League, Justice League Unlimited, the three of four movies. Listening to the director's commentaries on some of it is amusing.
In regards to one episode they had a fantastic comment:
"Now, this robot here is actually inspired by the one from Laputa. Now Hayao Miyazaki said he was inspired by Max Fleischer's Superman when he came up with how that moved, so I figure we're just returning the favour"
and a second:
"Now the spider-like movement here is fantastic, I can't remember where you got the idea for that from..."
"....Legend of the Overfiend"
Other than that stuff like Ducktales, Family Guy, American Dad, and Johnny Bravo.
Oh, and my current favourite (Which Nickelodeon have had on hiatus for MONTHS), Avatar: The Last Airbender which needs season boxes in the UK, dammit :/ My only upscaling DVD player is region 2 only