dartar, I use Quicksilver to jump to my System Preferences > Energy pane. That lets me quickly access the amount of time until the computer sleeps, so it's quick at night (when I leave it running but don't want the screen on) and quick to set a longer delay for work.
I assume you know how to do that and are looking for a way to actually change the setting itself? Sorry to say I can't help (not being a programmer) but agree it would be a great, useful tool.
