Crowd Sourcing Seen Everywhere

I have been recently seeing a lot of examples of crowd sourcing.That is for example:

- Ad copy

- Community project Mostly it seems like its being used for brands as a marketing tool / viral / we are so hip and cutting edge tool.Here are some things I'm will think about regarding crowd sourcing as I drive home tonight:

- What are the key elements that actually make people interested in participating in this? For me personally, I've experimented with ConceptFeedback. I guess I like giving my feedback because I feel I know something about effective design. Yet as someone who doesn't design myself; there isn't a whole lot to keep me coming back to the site.