I am using a Zoom BT card in my work laptop to sync to my iPAQ.
Here is a
link to the products page on Zoom's site.
Note: It is not 100% flush with the edge of the laptop, the little tab sticks out just a tiny bit. It does not stick out as much as a USB dongle does. I do leave it in my laptop, which travels in a laptop bag, causing no problems with the card.