Here's some of the more basic sites that everybody should know of, but are still good to have links to:
http://articles.elitefts.net/ -Probably the most popular strength training website on the internet right now, always has some quality stuff. The older articles are some of the best, any of the EFS Classics are worth a read. I shouldn't even have to provide a link.
http://www.liftbigeatbig.com/ -A bit more Olympic-lifting oriented, but has some good information.
http://www.deepsquatter.com/strength/archives/ -Pretty old school stuff here, lots of articles and interviews with some of the best powerlifters of all time.
http://www.joeskopec.com/ -Has lots of program spreadsheets, as well as some decent articles and powerlifter interviews. This is where I got a lot of my spreadsheets.
http://www.westside-barbell.com/ -The one and only. The older articles are the best ones, particularly around the 2002-2005 area.
I also have a collection of articles and stuff from various websites (mainly EFS) as well as a sizable collection of various classic powerlifting program spreadsheets, mainly linear periodization, but with a few others as well, along with PDF's of 5/3/1, 5/3/1 for Football, Practical Programming, Science and Practice of Strength Training, and a few others. If anybody wants them, just ask. If enough people want them then I can create a Dropbox or something similar for everybody to have access to them. All files were acquired legally.