If you create a funny/witty commercial graphics for your project, I'll include it as a trailing image in one or more (if more "commercials" are provided) of the levels in my game.
Basically, your image will be displayed when the player completes the level to where it's attached.
So the player completes a level, and gets some image shown with some text, "This level was sponsored by XYZ project" or "XYZ project really liked this puzzle" or whatever..
Here's a mockup I've made, for Linux.
Well, you get the idea

I'd ofcause be glad if you'd link back to my project in some way, but I don't really care, just thought it'd be a funny way to add some content to my own game, and maybe help others out in the process..
I included the .xcf for the mockup in case you'd like to use that as a base, but it's not required to use that.
Requirements:
320x240px, .png and I'd appreciate the source .xcf (gimp native format) if possible, but that's not required.
Your project must be under a GPL compatible (or free'er) license. (Like wtfpl)