Websites and search engines?

[halocentury]

I have used this community on many occasions, and have received very useful advice. I try my best to my own research before requesting help, but sometimes I don't know where to go. The extent of my searches usually involve wikipedia and google, but I know those aren't the only places that I could go to online.

And so, I ask as a general research-based question, for my own use and for everyone else interested, what other websites or search engines do you use for general-based topics? What do you use for specific subjects?