Free open source GPL instrument / musical chromatic tuner (like an electronic guitar tuner) for Windows, Windows Mobile, & Pocket PC. Displays name of note played & accurate indication of whether pitch is sharp, flat, or exact (relative to 440Hz A).
This J2ME app can turn your Java + WIFI phone into an extremely simple yet effective remote control / keyboard for your PC.
It was designed to be used with EventGhost (www.eventghost.org) and with XBMC in mind, but it can be customized for anything, since it limits to sending button messages and delegates all decission making to EG.