Work got me a corded Mighty Mouse, but after a couple weeks of using it, my shoulders were wrecked. So being the sort of person I am, I did a 'Dear Lazyweb' tweet, and shortly had recommendations for mice.
Aside from finding some awesome cool trackball mice, I also found what I now own: the Logitech MX Revolution. It met my critiera of rechargable, cordless, fits my hand, and compatible with linux and mac osx. As an extra bonus, it has lots of customisable buttons!
It is now happily integrated into my workflow, with change desktop, cycle through tabs, view desktop, and dashboard bound to various buttons. Yay new toy!