I'm one of those cheap people who never buy shareware ... I'll look for freeware alternatives with lesser functionality before I shell out my hard earned $. But this app offers functionality that is impossible to live without. Microsoft and Logitech make crap drivers for Mac OS X, but USB Overdrive takes over where these others fail. Now I've purchased a Logitech MX1000, and its nice to see USB Overdrive able to configure all the buttons, even the side-to-side scroll wheel functions. This is the only shareware app that has earned my money and respect, so it also earns 5 stars. (I haven't installed Tiger yet; will next week. I hope all works well)