OK, I know everyone's going to roll their eyes with this but, as I've not done speedruns before and I have trouble with mustering patience for such things, here are some suggestions for games other people might want to try doing speedruns for. I'll list the inspiration, the game, and the platform(s).
I was VERY impressed by the Battletoads speedruns by Phil and Genisto. That's why I think someone needs to speedrun these games:
Super Battletoads (SNES)
Battletoads and Double Dragon (NES, Genesis, SNES)
Also, does anyone know if the Genesis version of Battletoads is as glitchy as the NES version? It might present a challenging speedrun all to itself if it lacks some of the glitches (including the fatal 2P glitch later in the game).
Super Ghouls and Ghosts on the SNES or Ghouls and Ghosts on the Genesis seem like they might be good for a speed run.
The 2 Vectorman games on the Genesis also seem ripe for a speedrun.
If there are any takers I'd love to see the results. These are all games I've found amusing but haven't managed to beat because either I was lazy or too distracted :)
Oh, and before I forget, there's a sweet Castlevania game on the Genesis with two somewhat different characters. That opens the door for comparative speedruns.