If I stick to things I've bought and that are in the same ilk as the Pandora, then I've only really caved into the Nokia N810 which I tested a couple of years ago and loved.
I've also reviewed the Dingoo A320 and still have it handy, although I'm a little addicted to the N810 at the moment.
Arguably I also picked up a Samsung NC10, but I got that before I pre-ordered a Pandora (I have been on the fence for a while) so I'm not sure it counts.
The list of stuff I've obtained/reviewed is too long, irrelevant and diverse to be worth posting. Although I think the BlueNEXT Bluetooth GPS and the MiFi 2352 deserve a mention because they're "compatible" with the Pandora and I fully intend to test them with it.
I'm also trying to get my hands on a selection of Bluetooth mice for a face-off review targeted at Netbook/Pandora users and will certainly pick up and test the new Apple Bluetooth Mouse/Keyboard if they're not complete lemons.
I've also tried a couple of
USB travel chargers from Proporta [excuse aff link], both of which are quite handy for powering a USB hub and attached devices amongst other things. These should come in handy for avid USB-peripheral using Pandora owners, although I used them to power a mouse and keyboard attached to my N810.