Word of the day: monomaniac
One who seizes on a single idea or subject with a pathological obsession.
Traded a few instant messages with a friend of mine last night. They were groping for a word to describe some of their cohorts who, while both gifted and sharing, are so totally focused on their field of expertise that they forego any other social normalities. Kind of like the people in news groups who know more about a product than anybody else... and they make sure you know that.
That leads me to another resource I want to mention: acronymfinder.com. This looks rather helpful indeed. Thanks to Eric Penne on the OLUG mailing list for pointing it out.