Kaj, this seems like a valuable approach (and it's a pity I didn't get to chat with you - RPG design has been on the forefront of my thoughts lately, and I inevitably think of the Kalevala (and fabbing and ip law by extension) when I go to a LW meetup, as Michael Vassar is the only other person I've met who has any familiarity with it!)

I've done this before with high success at general social events. However, I find myself doing it wrong sometimes, and LW meetups are one of the best examples of why: assuming other people have limited interests. Because the strongest common thread between most people in the SIAI house is a set of subjects in which I feel deficient, I find myself thinking about those topics, and with little confidence. This puts me in the mindset of listening, to learn and avoid embarrassment, but at the cost of fun and good conversation. If anyone else has this problem, it's a bland recipe for a self-fulfilling prophecy.

Given that, I'd say it's valuable not just to consider your reasons for wanting to converse (as Peter Lambert-Cole mentioned), but why other people might want to converse. You won't have as much fun as you could if you don't intend to, and you won't intend to if you strongly restrict your precaching due to false expectations of why other people want to converse (or about what subjects).

I also find that mild exercise and consumption of chocolate and mint before socializing tend to correspond with the finest conversations, but this is purely anecdotal.