I don't lurk, but i don't post unless i feel a need to contribute or give an opinion, either.
Sometimes it can also be safer to lurk than to say something you will later regret. You can say something without thinking about it, have it deemed offensive, and risk the wrath of the banhammer. It's much better just to lurk about the thread and say nothing at all.
It's nice to see lurkers make an account for the sole purpose of posting their opinion on something they feel strongly about, though, even if they never touch that account again.
I think we should encourage more lurkers to come out of the shadows and talk openly. Make the community bigger!