If you want an iPhone, you have exactly one screen size to choose from: 3.5 inches. On Windows Mobile, the size of the screen varies, but the resolution is stuck at 480x800 for the foreseeable future.
WIth Android, you can find super-small phones like the HTC Aria, which has a 3.2-inch HVGA screen, or you can find up to 4.3-inch screens on the Droid X or Sprint EVO. If that's not big enough for you, you can run Android on a 5-inch Dell tablet and use that as your phone.
NEXT: Voice actions
Last updated November 08 2010: 2:25 PM ET