There is a free app called Signal Location Utilities
F5 BlackBerry Utilities
you can see the signal strength and map the location of the tower you are using. I use google maps. It's supposed to map several saved tower locations at once using bb maps but I couldn't get that to happen. I don't understand most of the data but it's really interesting. I've installed and uninstalled it a couple of time with no problem and no significant battery or memory drain.
I've put a copy and paste of the about:
Signal-Location utility for BlackBerry
Signal-Location Utility for BlackBerry is a convenient place to view network and location information.
SignalLoc provides you with major radio information on the main screen plus a detailed radio screen with all attributes included. If available, the latitude and longitude of the cell site is also displayed. If the lat/lon is avaiable, you can also show the cell site on a map.
You can save and export cell sites to CSV or KML format and you can have SignalLoc automatically save new cell sites as you encounter them.
SignalLoc provides you with your current latitude, longitude, altitude, speed and heading on the main screen plus a detailed GPS screen that adds horizontal and vertical error and the number of satellites currently in view. You can also show the current location on a map.
You can save and export locations to CSV or KML format and you can have SignalLoc automatically save locations for you when you've travelled a specified distance.
Saved cell sites and locations (both considered landmarks) are stored in an internal database. From the landmark lists you can view landmark details, delete, export, and view them on a map.
SignalLoc provides a convenient screen to view device details such as battery level, battery temperature, Battery voltage, PIN, and memory statistics. There's also a memu option to view the system log.