This one is not for the faint of heart, but the guy over at Photocritic.org managed to rig himself a macro lens for
his Canon 20D using naught but a
Pringles can (that wonderful tool of hackerdom), a cheap
lens, and a few other odds and ends. The results aren't too shabby either, he manages to get some sweet pics with his
setup that are worth a look even if you're not quite brave enough to mod this one up.