glTail is a great little Ruby script by Erlend Simonsen (aka Fudgie) that uses OpenGL and Ruby to visualize the events taking place in log files in real time. An example video on the official site shows requests coming into an HTTP server, each represented by a "ball" which is thrown across the screen. The script uses net-ssh to connect to a server and then libopengl-ruby to output the graphics. Parsers are included for processing Apache, Rails, IIS and Postfix log files. Nice work! The code is merely a couple hundred lines of Ruby, so if you've fancied putting together a basic OpenGL app, it's worth looking at it for that reason too.
I can't wait to try it on a few gigs of firewall logs.