Researched them since I've used several with Palm Pilots and Blackberries. Best I've found, and although it's not foldable is the Apple bluetooth KB they sell at the Apple Store! I find it very easy to carry in my backback since it's so thin. It uses AA batteries, connects in nanoseconds and is flawless. It's $69 at the Apple store and can also be used with any bluetooth compatible device. I've used mine a couple times per week at long meetings taking notes (use Awesome Note for it's Google Docs syncing) for about 4 months now and still going strong. check it out!