Ever wonder how flies walk on the ceiling?

Things like this drive me nuts wondering about it. I once spent many hours watching flies land on the ceiling to work out how they land and take off. Think about it for a second... their wings are on their backs and the ceiling is above them... so how do they land?

Anyway, this isn't about that. This is about how their feet work for walking on walls and ceilings. Fascinating!
http://www.primidi.com/2006/04/07.html