I use an iPaq 3950 with Windows Mobile 2003. I've been refining an SQL Server database of edges/flaws, spells, cyber, bio, etc. and have been considering expanding it to hold complete character dossiers with journal entries, etc. and building a PPC app for the iPaq to sync such information in a SQLCE database and present it in forms on the iPaq. I could edit the info during game time and sync it back to the SQL Server afterwards.
Then again, I was always a bit of a geek...