Sometimes I wish that you could switch of gravity for some experiments, especially during some lessons at school. I’m sure my students and I would have as much fun as Don Pettit (his weblog is Letters to Earth) who uses his spare time on the ISS to do some fun experiments. I especially enjoyed watching Thin Film Physics, Goo! and of course the vacuum cleaner hose turned into didgeridoo.
By the way, his time lapse from space is also pretty neat.