Geysers and fountains!
Geysers and fountain's can be powered by pulser pumps.
I have only made one geyser and people found it very
interesting. The geyser would explode into life every few minutes and it
could be adjusted to produce a fountainy blast of water or a fine mist
and more or less everything in between. For a geyser or a fountain, you
need a clean water source and a pool at least 4 ft deep. The supply of
compressed air can be a pulser pump or perhaps a windmill working a small
Check the drawings for more details (they are not fully
complete but might help you)