On my Logitech mouse, I’ve got an Open Programs MaxMenu item associated to the click of the scroll button, Close Window and Hide Application assigned to the buttons above and below the scroller, A custom MaxMenu associated to the lower button, and Exposé functions associated to the side buttons.
So, what’s on your Logitech?
Update: As commented by Olivier, the Logitech software delivered on the Mac OS X platform, is, shall we say, … poop. If you’re using a USB device on the Mac, you need to be using the excellent USB Overdrive software.
On my Logitech is a Post-It saying “Damn you Logitech for not writing proper software for your mice to allow for a different button configuration depending of the frontmost application.”
At first I thought Logitech just didn’t care about Mac users, until I discovered that the Windows drivers have the same limitations.