Signal Meter logs, and graphs the strength of the signal that is detected by the BlackBerry. Signals can be either GSM, or CDMA, and in either 3G or 2G. SingalMeter is not currently set up to indicate if a signal has gone from 3G to 2G and vice versa.
Signal Meter can be purchase from Blackberry App World, Mobihand.com or by clicking on the Buy Buttons below.