Oh, I love the Internet Movie Firearm Database! I have absolutely no experience with guns and that has been so helpful and enlightening for me on so many occasions already... And I can't wait to check out the other links :)

I write a lot of h/c, so I need medical facts. And since I'm not a doctor or medical practitioner I need to find those somewhere. (Watching e.r. for fifteen years only teaches you so much, right?) And if I can't ask someone who knows a lot about these things, I found http://doctorgrasshopper.wordpress.com/ really helpful. Awesome writing style and really great information.

I'm fairly well read and have seen a lot of Europe and the US, so I use first hand experience for a lot of settings. And well, do Lee Child books count as research material for Army proceedings, ways to kill people and general bamf-ery????

Generally I'd say the better your research, the easier for the reader to immerse themselves into your story. You don't have to use all the details you learned (I'd strongly suggest not to, but that's just me), but it'll give you a better sense of where and how things happen and will make it so much easier to write :)