Nifty Now, Getting Great!
This script is by far the easiest way I've ever seen to eliminate banner ads, and that is only one of the first features this package supports.
Development is proceeding at a blinding pace, and the author has been more than receptive to my occasional comments.
The future for this script is actually that of a full-blown platform for processing and massaging network data on the fly, complete with a Web interface for configuration and management. A modularized expansion interface already exists, and is evolving rapidly toward maturity.
Get it, play with it. For what it already does, it is amazingly small. But be warned: You will need a fairly large perl installation to make this script happy, so be prepared for some visits to your local CPAN mirror.
An open, cross-platform journaling program.
A scientific plotting package.