where do you get banner designs?

[AdrianApe]

I'm dreaming of a hopefully not too far off time in the future when I have a high traffic site and can incorporate banner spaces that local businesses will be interested in renting.

Just curious how you design a banner. Is it just a GIF or JPEG with a link? I don't have any graphic programs and doubt my ability to make anything that doesn't look cheesy.

One of these days maybe I should get around to downloading that free graphic program GIMP and start messing around with it.

Just wondering what everyone does for their banners.