I enjoyed Mighty Mouse, but the New Adventures of Mighty Mouse that came out in the mid or late 80's was amazing. When you have a villain called Mole Momma that shoots baby moles from her nipples as a weapon on a Saturday Morning cartoon, something right is going happening. There was so much insanity in those cartoons. Also around that time was the great cartoon, "The Completely Mental Misadventures of Ed Grimly." It was basically a cartoon where Martin Short threw in his Katherine Hepburn, Montgomery Cliff impersonations regularly while the story centered around the Ed Grimly character. That was another of my favorites that I failed to mention.
Just an Fyi, small fry. The Transformers weren't by any means the original. Turbo Teen was, cartoon-wise. <object width="425" height="350"><param name="movie" value="http://www.youtube.com/v/7UevBVGMap4"></param><param name="wmode" value="transparent"></param><embed src="http://www.youtube.com/v/7UevBVGMap4" type="application/x-shockwave-flash" wmode="transparent" width="425" height="350"></embed></object> There was also a Dune Buggy that transformed back in the 70's, but nobody remembers that. Transformers were original in marketing. Nothing else.
I don't know if it qualifies as obscure, but Duckman was a great, short-lived series. Ditto The Critic... MTV used to have cool cartoons other than the obvious Beavis and Butt-Head: Liquid Television, The Head, Daria... I'm not sure how they hold up ten years later though. Current faves: South Park - head and shoulders above everything else Simpsons - even in down years is still better than nearly everything else Drawn Together - has flashes of brilliance, but at times can suck really bad American Dad - underrated.
I have a feeling the novelty on this will wear off, but the trailer and the first 60 seconds of episode one have been pretty damn funny. Assy McGee Trailer: <object width="425" height="350"><param name="movie" value="http://www.youtube.com/v/iUKAirLbsRU"></param><param name="wmode" value="transparent"></param><embed src="http://www.youtube.com/v/iUKAirLbsRU" type="application/x-shockwave-flash" wmode="transparent" width="425" height="350"></embed></object> First 60 seconds: http://www.adultswim.com/shows/assy/
If you want to watch some old cartoons you haven't seen in a long time...go to http://www.rapetheweb.com. (oh...it also has movies, and tv shows....STREAMING) I can't believe they have 2 stupid dogs! hahaha.