I've been lurking on LW since shortly after it started, and on OB for about six months before that. In that time, I've told four or five people about it. I would make a terrible evangelist.
I'm curious as to whether other people have the same problem. I'd like to tell lots of people about LW, but I don't think they're ready for it. If they read a statement like "purchase utilons and warm fuzzies separately" their eyes would glaze over, and they'd walk away thinking LW was some sort of crackpot site.
I have found certain posts and topics to be fairly good hooks for getting people interested. An Alien God is a good suggested read for people with an interest in evolutionary theory and the Cthulhu mythos (surprisingly high crossover in my experience). HP:MoR is also a pretty popular hook. The site itself isn't really optimised for word-of-mouth, though, and not everyone likes child wizards and blasphemous horrors.
How many people have you introduced to LW? Who were they, how do you do it and what was their reaction? How could we do it better?
I wrote large chunks of the RationalWiki article, which has actually attracted RW readers. LW is an interesting site even for lurkers. Someone started an EY article too.
So, start an article or post a relevant link in your preferred social space as relevant. Taking care to set a good example, since humans tend to judge ideas by their advocates before they judge the content, irrational or not.
(I myself consume LW as a work-avoidance amusement somewhere in with Slashdot, RW and answering all my email (one of my most effective recent life hacks was to actually keep Gmail closed and not check it more often than hourly), so I may not be the best example to follow.)