PachTweet 
Send Twitter Direct Messages to update a Pachube feed. You must, of course, have a Twitter account to do this! This is great for controlling things via Twitter: just have your device/arduino/environment listen to the Pachube feed for its instructions.
Please note, Pachube.com privacy options will be introduced in early 2009, but for the moment all Pachube feeds are public - however since you will send all your Twitter commands by DM, no commands will be visible to the public. All commands take a minute or two to process.
