Intrepid Hudson user Christian Pelster posted a little project of his this week to the "users" mailing list called: hudsontrafficlights.
Christian describes the project as:
This Java based daemon aggregates the status of one or more jobs from a Hudson continuous integration server into a single status (red, yellow, green) and invokes a shell script on status change.
You can use hudsontrafficlights to control a USB traffic light (such as this USB Traffic Light from Cleware, GmbH) to give you and your colleagues nearly instant feedback on jobs in Hudson, without ever needing to leave your text editor!