You can easily build your own ad-hoc HipChat add-on to send or receive messages from your own custom applications. Here's a quick 2 minute tutorial video:
Log into hipchat.com, and go to Rooms > Integrations > Find New then click on "Build Your Own".
Have you developed something that you would like to notify everyone once it completes executing? A build script, tests or deploying code? You can add a simple POST script that sends a JSON package to a HipChat URL and it will post a message in the HipChat room.
By creating a REST endpoint in your application you can invoke a message to be sent back to HipChat. Perhaps checking on the status of your build script or perform a search and return the results in HipChat. Here's how it works: