Anything, but not games. Since I'm a programmer, the list of these projects will be the longest, here you can find anything from Simple webapps, to expert trolling machines. If you find any kind of bug any of these, please use the site's bugreporter, instead of emailing and stuff, If fixing the bug requires get in touch with you, I'll email to you at the adress you included in the bugreport.
Most of these are free, but feel free to donate me using the button on the left. I hope at least one will be useful for someone.