There exists a protocol named ANT+ which is touted as a low power wireless sensor network. Many devices use it, in particular bicycle computers and heart rate monitors. It apparently uses frequencies in the 2.4GHz band. I know there are many transceivers in the N900. I was hoping one of them could be made to work with ANT+. Even though I am a developer, I have never worked with wireless protocols or RF in general, so I thought I would ping on others here before going on a wild goose chase.
Some Linux software already works with the protocol using a USB adaptor that is basically an ANT+ to serial adaptor:
Talk thread here.