Mike Tyson's Jungle Beat
Each bongo has a top and a bottom button. These naturally correspond to high and low punch. To dodge, clap. To use your star punch (or to "Press Start"), hit both top buttons. To block, hold the start button on the bongos.
Download mtjb.zip to get started! mtjb.diff is the patch from the SVN trunk as of today (June 27, 2008). The hack is pretty straightforward, so it's not very large. InjectorSrc.zip is the source code for the injector program, in case someone wanted to compile a Mac version or something.