What do you use when responding to questions?
Your brain, reference books, the net, other people's knowledge?
What's the most popular?
I would say a combination of brain (?) and net for me.
Depends on the category the question is in usually......Mostly the same two as you but I have a large library at home (nearly 2,000 books) and use this if I know the info will be available in there.
It's a mixture of opinions - always my own, and the ludicrous amount of trivia I seem to have filed away in my brain, and for music, an equally ridiculous amount of factual information which I appear to retain with no concious effort what so ever.
I use my own knowledge and rarely look something up else I know it's there and just need to find the URL. At the end of the day, the person who got as far as this site can go look it up in Google for themselves... Why the hell should I do the leg work and present it all on a platter?!
If I know something, that's it, if I'm not sure but have an idea I have a collection of reference books, maps and dictionaries, and if it's about a product or specific thing not in my books, then I'll do a net search.
Brain (often confirmed by a net search), reference books and me mum. When there's a question I know nothing about, I enjoy searching the internet and usually end up spending too much time learning something new.