LMMS, MyPaint, CCleaner, and an app I developed called CamDesk.
Well LMMS (Linux MultiMedia Studio) is great for producing music, and a great free alternative to FL Studio (aka Frooty Loops) and I use it quite a lot, however I think it'd be so much better being a portable app, not only with it being portable, but I like portable apps, cause of that, as well as when I uninstall an app for whatever reason they usually leave extra files, and stuff in the registry in which I feel should be removed as well.