CMU's robots are called STRIDE, for Surface Tension based Robotic Insect Dynamic Explorer. They mimic the way water strider insects "walk" on water.
I wanted to see how difficult it is to make a "robot" that moves on top of the water surface, purely based on surface tension. I found out that recreating the principle is not hard at all.
When carefully putting the construction on the water, the surface tension keeps it on top. When disturbed, the construction sinks, proving it is really the surface tension that does the trick.
The vibration of pager motor gives it some rudimentary propulsion (both on land and on water actually).
I hope this experiment inspires you and I look forward to hear what you can do with it. And of course, your vote is welcome.