Xautolock monitors console activity under the X window system, and fires up a program of your choice if nothing happens during a user configurable period of time. You can use this to automatically start up a screen locker in case you tend to forget to do so manually before having a coffee break.
xlockmore is an enhanced version of xlock. It incorporates several new commandline options, which allow you to run it in a window, in the root window, in a different size/location, change the size of the iconified window, to install a new colormap and delay locking for use with xautolock.
Snow Path Formation Simulator is a program that models the process of people forming very distinct, and yet not always altogether logical looking, paths in the snow as they walk across open spaces. The evolving condition of the snow is displayed graphically. This project may eventually mature into a screensaver.