Logitech's $70 Ultrathin Touch Mouse T631 for Mac is a wireless input device that complements Apple’s various MacBook models. Designed for travel, it’s thin enough to slip into your computer bag without adding much bulk, and the touch surface on top lets you take advantage of OS X’s Multi-Touch gestures. Like Logitech’s Easy-Switch keyboards, the T631 can pair with two computers at once, letting you easily switch between them.
According to the company, one minute of charge time (via your computer’s USB port) gives you an hour of work time.
Updated 8/30/13, 12:30pm: Logitech says the T631 can pair with two computers at once, not three.