I just got my Zoom Bluetooth 56k modem lat week to use with my Axim X30 Mid. Works well, and was not too bad to set up. I travel a lot, and the hotels I stay in don't usually have wifi, or even any kind of net access.
The modem itself is quite small, but the power cord is kind of bulky. It comes with a 6-foot phone cord, too. A software CD is incleded, but I didn't need anything off it except the user's guide.
The BT connection is only made when you want to dial out on the modem and only remains as long as you're online thru the modem. Set up wasn't really straightforward. After making the pairing thru the BT Manager (the passcode is the PIN on the underside of the modem), it wouldn't create a good dial-up connection. I ended up going into Connections...Connections and using "Add a new modem connection." This wizard was slightly different than the BT modem wizard, and worked better.
I have broadband at home, so needed some dialup acccess. I bought about 240 minutes or so from bamnet. They have an 800 number and it only takes a couple minutes to perform an ActiveSync and download my mail. Then I disconnect, read and write replies, then reconnect to transmit.
Overall, for $77 (free shipping from ecost.com), this was worth it.