There's been a lot of research on gecko feet - industry and government are very interested in finding a new, strong, reusable adhesive method. Gecko feet are "sticky" because of millions of microscopic hairs that use Van der Waal forces to adhere to a surface.
Here is a video to a robot developed at Stanford University to climb using gecko-type feet:
http://www.youtube.com/watch?v=ECpY2N5rgcM