“The internet is like a herd of elephants with diarrhea…there is a non-stop flow of s**t and tons of it”
You just have to search and ye shall find.
Seriously, that is such a hard question to answer. Of course, google, yahoo and other search engines are useful. Airliners.net is indispensable (with the above stated axiom fully applicable). Also, you can search Yahoo groups for a SIG that tweaks your fancy and join it.