A few years back, a Hayabusa-riding roommate of ours was dating a Geo Metro-driving friend of ours. The relationship didn't last, but during the brief romance, we discussed with said roommate the prospect of replacing the Metro's 1.3L Suzuki mill with the rather more potent unit from the sportbike. This character aimed a bit lower, dropping a 600cc Honda bike mill into a Metro, and now he's listed it on craigslist for a paltry $2,500 bucks. We'll leave it up to you to decide whether it's worth it or not. [Thanks to Larsen for the tip.]

Superbike Powered Geo Metro [craigslist]

SUPER RPM AMUSEMENT! Hayabusa-Powered Starlet [Internal]