I think once we get a large enough archive of these I will go through and rename them and put them in folders so that they can be installed quickly and easily.
For example, the Atari 2600 emulator by default just uses "icon.png" and "title.png", so I'll create a folder named caanoo-a2600 and rename the new baricon files and put them into that directory. I'll do that with all of these and then I'll zip them and upload them so that everyone can just drag the folders they wish to use to their games or apps folder and the icons will replace the originals immediately.
I'll start getting some together right now, but I won't upload anything to OpenHandhelds until you guys feel you've covered everything you want to cover right now.
EDIT: As a side note... I think the "S" logo for Scummvm is very recognizable so I made an alternate icon using that. What do you guys think?