I came across this great Slashdot thread about what to do with "great" ideas. The comments are the best part: the basic gist is that you should not keep your ideas to yourself but rather socialize and spend your time and effort on figuring out how to collaborate with others to get them done.
"Got an idea for a better mousetrap? Build it and see if it really is better. Talk is cheap and action speaks louder than words."