Rather than a formal taxonomy, this diagram by Ibrahim Evsan divides geek culture into activities, obsessions, social communities, terms, idols, and types. Its primary flaw is that it does not take cross-breeding into account. Larger version at the link.
Link via Fast Company
Never "Legos"
"Legos" is like saying "Heinzs" or "Kleenexs" or "Sonys" or "Apples"
It's incorrect to say "have you seen my Sonys?" just as it is with "Let me show you my Legos"