Put Xgrid to Work
If you're running Tiger then Mac you are currently using can be used as a node in a powerful network based computational monster (and if you're on Panther you're a download away from joining in on the fun). Everything you need to use is baked right into the OS; which boils down to a combination of Bonjour and Xgrid.
Drew McCormack at the MacDevCenter has penned an article showing how to setup an Xgrid agent on your machine and start clustered operations with a few clicks of a mouse. However, the real power of Xgrid lies within the inky depths of the Terminal window, so if the very thought of typing commands makes your legs quiver this article might not be for you.