Most lawyers use the Blackberry, but I'm sold on a recent addition, the Sidekick 3.
From various reviews:
In my experience with a BB ... it has an awkward interface that mocks rules of good design. Clicking on a link on a Web page should take you to a new page, but here it invokes a menu many items long. Opening a memo requires choosing between reading it and editing it; when you close a document, the default action is to discard your edits.
T-Mobile's Sidekick 3 does not have that problem. It has an LCD screen that slides open to reveal a QWERTY keyboard that falls right under your thumbs, with the important controls (on either side.
The Sidekick Web browser and e-mail program are far more approachable than the BlackBerry's. Mine also has instant-messaging software for AOL's, Microsoft's and Yahoo's networks. We use IM at home and to a certain extent at work.
The Sidekick it has a higher-resolution camera, Bluetooth wireless, and MP3-only music playback.
I'm sold on it more than anything else because the size of the keyboard and the screen size help this greying litigator see each without squinting.