Other
Pulley Basics
Here are some animated drawings of a fixed pulley and a movable pulley. Then, of course, there is the combined pulley which makes life even more easier.
Walter Fendt
Walter Fendt: Sistema De Poleas
This site is an interactive applet using the principles of a pulley system. The number of pulleys can be varied as well as the load lifted
Other
Colts Neck Township Schools: Hands on Technology: Marvelous Machines: Pulleys 2
Student handout for conducting an experiment in using one pulley or two pulleys to lift a load.