I am discovering that wine corks seem to provide solutions to a variety of bike related annoyances. I stumbled across this cool hack on Kevin Kelly's site. It's a simple yet brilliant idea for an age old problem.
I know some brakes have the ability to be engaged when the bike is not in motion, but I have seen very few. And if you don't rock a kick stand, you often return to a bike on the ground after you have leaned it against something only to have it move on you. I know I for one could have used this idea before as my road bike has a huge dent in the frame because it fell over into pole at a rest area one time. I'm pretty sure this would have kept that from happening.