I'm not sure if it will be obvious what these are at first glance....
Basically, they're platform pedals that "clip" in to your clipless pedals. This way when you want to wear flip flops and ride your nicer bikes you can. The idea is simple and pretty well executed. Just install your cleats onto the bottom of the platform and with a little cussing and swearing you can clip them on to your pedals.
It's also a great problem solver for those of us who commute to work and then occasionally ride home with wifey, leaving the bike and shoes in our office. The next day when we think well just ride another bike to work....we are left without proper shoes to use our fancy pedals with! This solves that problem.
Overall they work well, as long as you flip them upright with your toe (they tend to hang upside down) before really pedaling. If you do just try to get going without flipping them over, the egg beater style (Crank Brothers) pedals will sometimes compress the spring and drop the pedal on the ground. I don't think this would be as much of a problem with SPD style clipless pedals. Unfortunately, it's just how the Crank Brothers work....but once you get the hang of it they do work well.
Anyway, it's a neat little addition to your kit that might be interesting to some people...and about as close to a product review as you'll get on this blog.