Fun with the Leidenfrost Effect :
Students at University of Bath in the UK had some watery fun with the Leidenfrost effect. What is it? When a surface is significantly above the boiling point of a liquid and comes in contact with it, it produces an insulating vapor layer which keeps it from boiling rapidly. You can see drops of water skittering on a pan in the kitchen... its a common occurrence.
From Physicsworld: It turns out that if you replace a smooth surface with the sort of asymmetrical teeth found in a ratchet, the drop will move rapidly in one direction. By using ratchet surfaces to accelerate liquid drops, the team has made the drops move uphill and even follow a predetermined path through a maze.
http://www.youtube.com/watch?v=vPZ7sx3EwUY
http://youtu.be/vPZ7sx3EwUY
http://blog.physicsworld.com/2013/09/09/leidenfrost-drops-race-through-a-maze/
Related Article
http://physicsworld.com/cws/article/news/2012/may/17/levitating-drops-controlled-by-fridge-magnets