Milab at the Technical University of Denmark used a Nokia N900 and an Emotiv EEG headset to have data from a brain processed and displayed on the phone. The raw data can be passed along to a storage device or computer for further processing. A brief synopsis can be found at the Milab site and a brief article can be found at Singularity Hub.
It would be interesting to have this record what happens during meditation, especially with something like Holosync that leads you through the different brain wave stages. Of course, the program is not located on the Android Market and probably not on Apple's App Store.