I think the best sigs are the ones that have composite backgrounds, rather than just dropping your name over an image. If you look at some of the stuff Venom has made, he uses a lot of brushes and filters to build up the background. (well that's what it looks like to me)
I think he mentioned "grunge" brushes a bit further back in this thread. Try Googling for some for either PS or GIMP, whatever you use.
Also Marvin, that ain't "graf" LOL. Please don't ever use a "graf" font, they're wack as all hell. I can't say I really like your background, but I tend towards darker sigs myself. And of course there's a fill tool... MSPaint has a fill tool XD Google it!