Unselfishness — For people who consistently post good answers in obscure or low-view tags.
Despite the joking about Objective-C fanboys, one of the perennial frustrations is that so few people view or vote on questions in that tag. My highest-voted SO answer was (still is) a semi-flippant one to a question with a Java tag. :-/
Sure, we post for a given language because we love it and/or use it all the time, but also because we care to help other users of the language. Nobody's hating on the Java or C# dudes, probably because they're in the majority, but does that necessarily make one any less of a fanboy? :-)