I don't know about the Labiatech mouse, but you can get buttons to spare on any of the new Logitech models. Most of the buttons are positioned in next-to-useless places if you ask me, but the one directly in front of the wheel isn't too bad. Especially if used for something like Paste operations.

I only use 2+ button mice with Mac OS. If I'm using the Powerbook without a mouse, then I'll try and use keyboard shortcuts and controls for as many options as I can remember, and try using the pad and single button as little as possible.

Bruno