Fluther has a huge variety of people, and there are plenty who are seriously into technology. There’s also the “discussion” element here, and people interact and there are several responses from several people to each question.
Aardvark throws out the community concept entirely by simply seeking a single person who will most likely be able to answer your question.
Quora seems a bit similar to Fluther, but it does seem to be a very serious, general site (only looked at one question about sushi, so I might be wrong). Unhelpful answers are “downvoted” and are collapsed out of view until you expand them manually (I like that concept somehow).
StackOverflow appears to be very social. However, this is basically a Wikipedia Q&A. From the FAQ:
“Other people can edit my stuff?!
Like Wikipedia, this site is collaboratively edited, and all edits are tracked. If you are not comfortable with the idea of your questions and answers being edited by other trusted users, this may not be the site for you.”
Eww.
And Yahoo… Why did you even put that as an option? xD