RE: PALM 5250

I went from a Treo 300 to the 600 to the 650.  The 650 is by far the
best unit of the bunch.  Still not perfect, but definitely a step up
from the 600 and miles ahead of the 300.

I've accessorized my 650 with:
Cardo Scala 500 Bluetooth headset
http://store.treocentral.com/content/accessories/9-32--165.htm (can be
had cheaper elsewhere)
A couple of retractable sync-n-change cables (early one + new one with
Hot Sync button)
http://store.treocentral.com/content/accessories/5-19.htm
Car 'USB' adapter to charge in the car using the above cable
Screen protector (change out every few months)
http://store.treocentral.com/content/accessories/15-43--28.htm
Pouch case
http://store.treocentral.com/content/accessories/4-25--245.htm
1GB SD card for backups & MP3s

Besides the Mochasoft emulator, on the software side I've got:
MobileTS for Windows Terminal Services
Mergic VPN for PPTP VPN access, and MovianVPN for IPSec
Adobe Reader (sucky, but slightly better than nothing)
Docs to Go Premium for MS Office functionality
BackupMan for scheduled backups of the Treo's RAM to SD
HandZipper for Zip file processing
pTunes Deluxe for music playback (MP3, WMA, etc.)
Ringo - works with pTunes for MP3 ring tones
LauncherX replacement app launcher
TreoSelectText to select text with the 5-way
ShortCut5 for keyboard 'macros'
pEdit Pro for large text file support
And a bunch of other stuff.  Misc. stuff + games, etc.

www.palmgear.com and www.handango.com are the most common sources of
PalmOS software.

Also, ensure your device's firmware is up to date.  New firmware
releases come out on occasion and fix stuff, improve performance, etc.
For instance, there's a new update just being released for Sprint and
unlocked GSM Treo 650s:
http://www.treocentral.com/content/Stories/618-1.htm 

The forums at www.treocentral.com are full of info (and useless rants,
etc.) about various tweaks and neat stuff.