Port Monitor and Alert Utility

I would like an application that can sit in my systray and monitor [at a configurable interval] for open ports on remote machines then alert me of changes by means of a "Bubble Message".  This application could have numerous uses such as:

1. Monitoring port 6112 on a friend's IP address (or DNS name) and alerting me when it becomes open.  This would tell me that he/she is playing a network hosted game of Diablo II (or other Battle.Net game) and I could immediately jump in to the hosted game.

2. Monitor port 80 on my webserver and pop up a bubble to tell me if it ever closes so that I may go attend to my troubled website.

Essentially I just want to be able to have realtime alerting on network services (NOT Windows services) being available or not available.

Snork.