Topic: Lisp
Here are a couple of Common Lisp tutorials that I have recently rediscovered and think are worth sharing:
The first is Chaitanya Gupta's tutorial on the CL condition system. The examples provide a good guide to how restarts work and how you can use them.
Next is Adam Petersen's tutorial on building web applications using Hunchentoot, CL-WHO and Elephant. It shows all the necessary basics from beginning to end, and I like the no-framework approach to web development Adam is demonstrating. There is even a little use of Parenscript to generate JavaScript. Overall an excellent tutorial.