The Coby DP-151sx Digital picture frame keychain seems to be ripe for hacking. At roughly $9, you get a screen, and Li-Ion battery. That’s not bad considering a similar screen alone would cost $20 elsewhere even though it runs on a slower serial connection. While they’ve only put a 3 color pattern on it so far, more can’t be far behind. If you don’t feel like actually tearing it apart, there are some projects that have managed to customize what it displays via the USB connection.