For mobile application you can choose from a range of devices, from manufacturers such as HTC, iMate and HP. Here are a few examples:
HTC TYTN
Good screen resolution, compact size & slide-out keyboard.
HTC TYTN II
As above but with built in GPS.
i-Mate Jasjar
Easy to read screen, large keyboard.
TC P3300
Compact form factor.
Toshiba Portege G900
Large screen & slide-out keyboard.
E-TEN glofiish X800
GPS Enabled.
E-TEN glofiish M700
Slide-out keyboard & GPS enabled.
HP iPAQ hw6915
Compact design with GPS & QWERTY keyboard.
