This section is really for feature ideas you're interested in actually working on.
As it stands, "cellphone games" is pretty meaningless and vague.
Etch-a-Sketch style graphics editor - this would be possible and sounds like you just mean alternative controls for the existing graphics editor (assuming they don't already have these controls, I don't use it).
As for DRM, Rockbox itself will never support DRM. Permanent DRM loss is avoided where possible, already.