If you want to mess around with modding your Kindle but you don't want to deal the wires and extensive case modding that comes with most hacks, this clever mod puts a Bluetooth receiver in your Kindle.
Over at Griffin.net they were scandalised by the lack of support for PDF table of contents pages in the Kindle which started their quest to mod a kindle and install third-party applications that would remedy the glaring oversight. Unfortunately a lot of the hardware mods for the Kindle make it particularly ugly and add bulk onto it. Since they didn't want to make it less portable or look like a franken-build they opted to access the Kindle via Bluetooth so that all their tinkering and modding could be done wirelessly.
The process requires that you open the Kindle case and do a tiny bit of case modding (removing a little of the internal plastic shell to make room for the Bluetooth unit) and solder a few points. Once that's done you can effectively telnet right into your into your Kindle and start tinkering and installing some of the third-party tools intrepid Kindle hackers have cooked up. Check out the article below for more information on both the hardware hack and the software they installed.