I am mainly posting just to say I think your avatar is hilarious, Icedemon :D.
On a more serious note, I think 1 project at a time is best. That's all I can handle, anyway, without getting side-tracked. Yeah, if you have crazy ideas I think it'd be beneficial and refreshing to stop your main project for a few days while you hammer out a quick and simple prototype (no graphics, just primatives / quick programmer art) to get a gameplay idea down.
But yeah. Anyone who can manage multiple projects at the same time (while finishing any of them) is an indie god. I'm having trouble getting progress done on my single project. Lack of coding experience and the time it takes to learn as you go really hurts productivity.
Er...final thought. Based on your posts, start with something very, very simple. Get something completed under your belt. Maybe something with the depth of Ikiki's Games