Our landing page conversion is hovering around 14%, which sounds like the higher side from what I've heard. My guess for why it's higher is because we've been targeting very specific people within our community. We chose launchrock for it's simplicity, but having done more research, I'd like to try unbounce the next time around (better integration with other services, more options).

Quora has some interesting posts on the topic (http://www.quora.com/Landing-Pages). For reference, our landing page is http://beta.opperator.com