Paint a few white and place them outside on the grass so
people wont park on your lawn.

Use it as building material. (This is actually what the
Ancient Egyptians used to build the Great Pyramids.)

Keep one under your pillow for home defense.

Send one to the junk mail company with a note asking them
to take you off their list.

Its colorful, use it as a Yule Log.

Carve the Presidents faces in one and submit it as a
science project.

Give one to your boss and tell him its a life preserver.

Use it as a base for flower arrangements.

Donate to the local airport for use as airliner wheel
blocks.

Grind a few up and give it back to your in-laws in a bag
marked lawn fertilizer.

For a community project, sink a few in the ocean and build
an artificial reef.
Tie one to each foot when you walk through deep snow to
keep your feet dry.