Conventional adhesive tape sticks when pressed on a surface. A new gecko-inspired synthetic adhesive (GSA) does not stick when it is pressed into a surface, but instead sticks when it slides on the surface. A similar directional adhesion effect allows real geckos to run up walls while rapidly attaching and detaching toes. The gecko-inspired adhesive uses hard plastic microfibers. The plastic is not itself sticky, but the millions of microscopic contacts work together to adhere. The number of contacts automatically increases to handle higher loads. A feature of the hard plastic gecko-inspired adhesive is that no residue is left on surfaces as is left by conventional adhesive tapes.

See http://robotics.eecs.berkeley.edu/~ronf/Gecko/interface08... (less info)