ArduinoCommander is a sweet new Android app for controlling Arduino with a Bluetooth shield.
From Android Market:
"Control your Arduino board from your Android device via Bluetooth using WYSIWYG interface.
- discover and connect to Arduino board with Bluetooth shield (like Sparkfun bluetooth modems: http://www.sparkfun.com/search/results?term=bluetooth+modem&wha...)
- display board firmware version, name and Firmata protocol version
- set pin mode (analog/digital input/output, pwm)
- get/set pin values
- read messages from the board (Firmata String Sysex message)
- beautiful WYSIWYG interface with 320x480, 480x800, 480x854, 1024x600 and 1280x800(?) screens support"