The only problem with the Earth's magnetic pull thingy is that it reverses itself every long time or so...though if someone can harness it and make it do their work...well...

Whenever someone mentions perpetual motion machines etc. I always start thinking about using gears et.c to power dynamos which power gears to power more dynamos......no way it would work but...that's what I always think about for some reason...

Water...could water be used in perpetual motion machines???