BIG EDIT: Arg, DogDoo beat me to some of them. I don't feel like going back and editing all of them out, so blah!
You forgot some of the names Quimbly, but good job, they're pretty much all there. It's pretty much everybody we've seen from Season Two, including the number 9 guy!
(alien woman above Slurm truck) That would be the Grand Council Woman from BBA
(pink robot)? The Crushinator (first appeared in The Series has Landed, but Season Two would be Lesser of Two Evils)
Slurms McKenzie (or someone else?) That's would be Glurmo
(I can't remember the refridgerator-like robot's name) That's Boxy, always the villian in All My Circuits
Hippie dude- Free Waterfall Senior (gets eaten by Lrr)
Old Lady- Hattie (annoying and in alot of episodes)
(Some guy hiding behind the "A" ) Looks like Professor Wernstrum
There's also a couple more, like the ameoba woman who won the beauty pagent (LO2E), Anglelyne from Bendless Love, Sal and Petunia, Fishy Joe, Mayor Poopenmeyer w/Brain Slug, and Mom with her 3 sons (The only son's name I can remember right now is Larry) and the hair robot (I'm a pretty girl!) I love that line. And the Hyperchicken.
Whew, that was long. I probably missed one or two, and probably mentioned one already mentioned. Oh well. That is definitly a cool picture, though.