The Trampoline Mod makes the sponge block into a trampoline block. If you walk on top of a sponge you will launch up into the air. Up and down you will go.
The block can be used in several funny ways. For example, you could include the sponge block in a parkour map when longer jumps are required. You could also build a swimming pool (as we did in the images below) with a trampoline.