The MDA, designed and made by Taiwan's HTC, a leader in the Windows Mobile "smart phone" market (they seem to make all the WM phones sold in the U.S.), is really a cool concept.  It has a nice shape, a slide-out thumbboard that automatically turns the screen to landscape, and all the goodies that make up Windows Mobile: Pocket Office, Pocket IE, MSN Messenger, Windows Media Player 10, and tons of free software to download from the web.  Plus, it has wi-fi which works really well.