Do you use a mind mapping software program? Inspiration is my current dumping ground, and it's fine for my casual use, but something that makes it easier to group and connect similar ideas would be nice, not to mention something a little prettier to look at. Tinderbox, OmniOutliner and some of the opensource programs at the wiki mind mapping page seem to be candidates. I use Mac OS X and am a casual GTD beginner, using a backpack account for my various lists. Quicksilver is gold. Stickybrain doesn't do it for me.
My typical inspiration use: jotting notes directly into the diagram view using rapidfire mode. Outline view doesn't do it for me.