I recommend the GlobalSat BT-359. I've been using it for quite some time and have been extremely happy with it. Also, it is the recommended receiver for TeleNav. No other BT pucks seem to work with their latest version of the software. I'm not partial to the BT-359 (other than I have one) but you might be interested in this thread:

http://www.blackberryforums.com/gps-...-feedback.html