There are two things that people missed the most after the demise of the 500cc two strokes, and their replacement with the 990cc four-stroke MotoGP bikes: The noise and the smell. You can still experience the sweet smell of burning two-stroke oil by standing as close as possible to the track as the 250 and 125 classes howl by, but as fantastic as the smaller bikes sound, they're still no match for the crackle of the 500cc four-cylinder two-stroke machines.
Fortunately, Honda have a solution: On their historic website, they are offering brief sound clips of the championship-winning Honda NSR500 machine. The files are in MP3 format, and can be downloaded to a modern mobile phone for use as a ringtone, for example, or just for the sheer enjoyment of hearing an old NSR500 on full song. The NSR500 MP3 files can be downloaded from this page on the Honda website, part of the larger NSR500 history site at Honda.