Statistical Mechanics in a Nutshell - An introductory text book online.

Monte Carlo Simulation for Statistical Physics - A brief online text book on Monte Carlo Methods

Entropy - Online journal intended for collegiate audiences. Provides links to web-based articles as well as some "basic" lessons on entropy.

Statistical Mechanics of Disordered Systems - Concentrated Advanced Course by Professor Anton Bovier (Berlin). University of Copenhagen, Denmark; 23-27 April 2001.

What Does Negative Temperature Mean? - A short article from USENET Physics FAQ.