If anyone is impressed (or even just interested), by the swirly graphic images I use in some of my banners, then I’d recommend you head over to http://fyre.navi.cx/ and take a look at the Fyre fractal program. It allows you to generate an almost infinite range of random graphics. This is free software, and I think it’s Linux and Windows capable – I’m running Linux, and it works great here.
Take a look at their banner page and you’ll get a quick idea of what it’s capable of.