Poynt -search near your location
Dilbert - Its free on Blackberry, £2.39 on iphone!
Forward Reply and Edit - Yes it should have been part of the OS, but its free!
Tube Buddy - Tube Map is great, but can never get the live departure info to work with that and BES. Tube Buddy works great.
Google Maps - Works much better than the inbuilt maps application
RSA SecurID - No more carrying around a jailers keyring full of hardware tokens.
Kayak - Nice app for searching for travel
Mailminder - Rules based processing of email (just like your Outlook/Notes rules)
BeamExplorer - good little file manager
GPSLogger - Create .kml and upload to Google Maps. Track runs, hikes, etc. Or just find your car in the carpark!
Opera Mini - About a million times better than the inbuilt browser
MidpSSH - Handy for SSH'ing into the servers late at night. Works through BES proxy.
QuickPull - Because having to pull the battery out to reset is just plain crazy.
Role Call Tasks Lite - A great little task manager
Role Call Reminders Lite - Turn emails into ToDo's just like you do in Outlook/Notes.
Now I need to go test some of the ones I don't have in the other posts. :)