I use a MacBook Pro, and when I'm not just using the laptop on my lap, my usual setup has it connected to a dock with an external keyboard and a Magic Mouse. The Magic Mouse doesn't give access to all the different gestures the trackpad does, but it does let you use two-finger swipe left & right for switching spaces, and a two-finger double-tap for activating Mission Control (showing all the windows of the active space, as well as the active spaces along the top).