Not for groups, but for individual people. When I talk about topics of general interests for rationalists with someone else, I often introduce them to less wrong. I tell them something along the lines of "There's a community of like minded people who likes to discuss similar topics on LessWrong.com".

I think something similar, i.e. organic recommendations can work for larger groups, you just have to use a different format. One idea would be to give a presentation and then add a final slide recommending to check out the website.