The Joinery contains animated illustrations of wooden joints coming together.
The website of Carl A. Eckelman, Ph.D., Professor of Wood Technology at Purdue University. Probably more than you wanted to know about joinery and cabinetmaking.
WK Fine Tools is an internet magazine devoted to traditional and fine woodworking. The site also maintains curated collections of downloadable woodworking books and tool catalogs and manuals. [more inside]
WoodTreks is a well-produced video blog about traditional woodworking with hand tools. Many of the videos are aimed at the beginner. [more inside]
The dovetail joint was once the king of joints. Mechanically simple and reliable, it's fantastically strong, but it's not simple to get right by hand. Nowadays, the joint has largely vanished due to the rise of flat pack furniture's reliance on screws and glues, but it still exists in high end work and in the hands of hobbyists. Most dovetails are now done using a jig and router to reproduce predefined angles, but every now and again you find someone who goes off and creates something truly beautiful. Like this box with hand cut double dovetails.