CTWM is perfect for my non-state-of-the-art boxes
Using a 500MHz laptop, I was tired of running KDE and Gnome as they just hogged too many system resources. They made my laptop unusable. Out of frustration I launched twm and ran Mozilla and saw a very responsive computer. Of course I need something a little more useable than twm, so after trying many window managers I settled on ctwm. I use it everyday on two older computers that would otherwise be slugs with bigger wms or KDE and Gnome.
You can get my .ctwmrc here (http://www.retards.org/ctwm/)
An open, cross-platform journaling program.
A scientific plotting package.