On message boards, a lurker is someone who reads the boards but seldom (or never) posts.
There are two main school of thoughts on lurkers. One says they are not pulling their wieght in posts ie it takes a certain number of points of view to make a board interesting and if one doesn't post, one is only "using" the board. The other school says that it is better to at least read if you don't have time to post or anything original to say.
I personally have no problem with lurkers.
BeeBee