Although, after thinking a bit, it'd probably be better if you looked for projects in the open source world that need help and worked on one of these. I don't want to be all like "oh you evil person polluting the internet with new code", quite the opposite (do what you want), but if you are indifferent to making something yourself and contributing somewhere, implementing some other person's project is probably going to be less "good for the world" than improving existing software.