We just added support for this on Zapier: http://zapier.com/zapbook/github/ We'll add some links to specific templates, but some good examples of ways to use it might be:
* Send SMS for specific mentions (we support filters)
* Power your own RSS feed (for Google Reader?)
* Dump to chat programs (Hipchat, Campfire, etc...)
* POST a JSON payload to some URL
* and many more...
Great execution, btw