One of the biggest bummers of traveling with a laptop is trying to use the built-in trackpad and nub to navigate. Apart from my general difficulty dealing with the cramped design, I always end up inadvertently hitting the pad with my thumb while typing, thus moving the cursor to elsewhere in the document. To solve the problem, I used to travel with a USB mouse, but I ended up not using it often because it was too bulky.
A smart solution has arrived. The MoGo Mouse is a wireless Bluetooth device that folds up to fit (and recharge) in a spare PC card slot in your laptop. A review of the mouse over at Cool Tools found that it was very easy to use. Have a MacBook Pro instead of a PC? MoGo has designed a mouse (available in June) to fit into your ExpressCard slot. Don't have Bluetooth on you machine? MoGo's developed a tiny adapter to plug into your USB port (available in June as well). Too bad the FAA still doesn't allow Bluetooth use on planes—this little mouse would be perfect for the cramped confines of a coach-class tray table.