Signal strength in numbers: Instead of looking at the bars, you can now change the display of your blackberry's 'signal strength' to read in real numbers. At the home screen, hold down the ALT key and type NMLL. The signal strength would now reflect in numbers instead of the bars. If you are in the 100 area ( -100 dBm), you will be transmitting at maximum power (2 Watts), and since coverage is hit and miss at this weak a signal, you may end up transmitting many times before the packets make it through. This might help explain any poorer than normal battery life. I consider anything at -90 to -50 excellent.
Note : To revert back to the bars: hold down the ALT key and type NMLL