The Ren and Stimpy Show - full run + unaired/banned episodes with commentary from John Kricfalusi and Billy West.
All my money, just take it!
i went back and watched some of r/s ... it's kinda gross when you watch it as an adult..
I remember it was just fine as a kid.. but now, it's kinda jarin'
the Ren's Toothache episode still haunts me 
Space madness, or Ren and Hoek
I think Lair of the Lummox and Space Madness are my favorite episodes.
I don't remember the Lair of Lummox. Will need to check that one out. Last I looked Ren and Stimpy was on either Hulu or Netflix. Though my wife has forbidden me from letting the kids watch it. I don't see that much of an issue with it as all they will see is the slapstick humor in it.
There's much heavier stuff on kids shows now a days, in comparison (I feel) Ren and Stimpy is rather tame. So much straight up violence and sexual themes in kids cartoons, and heavy themes that may not be appropriate for a 5 year old. A little vintage gross-out humor and cartoon slapstick seems so far from that.
Heck, I've seen more disturbing stuff in Adventure Time
)
* there actually was one episode that was banned for excessive violence:
Man's Best Friend-the scene where Ren beats George does seem in poor taste
