This is probably the most comprehensive how-to and DIY website I have visited. The user-submitted content offers instructions on how make or do just about anything, be it a delicious cake or a replica trebuchet. A true home to anyone who enjoys the sense of satisfaction garnered from a completed project.

I believe that the website describes itself the best:
"The preeminent Internet publisher of literature, reference, and verse providing students, researchers, and the intellectually curious with unlimited access to books and information on the web, free of charge."