I respectfully disagree. Because we have no major advertising campaign or other entry point most sharing of articles and getting people interested in the community is 'peer-to-peer' i.e. someone shares an interesting article with their friends or sends a friend a specific article they may be interested in. Facebook is an ideal medium for doing this as people of all social groups use it and it is a recognised format.
I personally have introduced many friends to LW via this method, and it is the primary way that people of college age communicate and pass on information. I don't think I'm particularly unusual in that my friends share, re-post and discuss articles on political and scientific topics with great frequency.
Even if we don't use the 'like' button, there are some changes that would make it easier to share. Aesthetically, currently if I post an article link I get an ugly text preview of less wrong tagline, rather than a summary/beginning of the article or a logo. This leaves us with a credibility gap when compared to other 'mainstream' news sites. [If someone can make the necessary changes to fix this issue I offer 100 of my karma]
Currently, LWers get +1 karma for a comment upvote, and +10 karma for a main post upvote. But clearly, there are other valuable things LWers could do for the community besides writing comments and posts. Writing isn't everyone's forte. Why not award karma for doing productive non-writing things? It's probably not optimal that karma and the community status that comes with it are awarded only for the thing that myself and a few other people are good at. For example, I really wish LW could award karma to programmers for improving LW.
The challenge is doing it fairly, in a way that doesn't alienate too many people. But there might be a workable way to do this, so let's explore.
Perhaps tasks could be assigned karma award amounts by LW editors (Nesov, Eliezer, Louie, etc.), or even just one person who is appointed as the Karma Genie.
Examples: