I wrote a thing a little while back, a love letter to OD&D (1974). It's available for free (Pay What You Want) over at RPGNow. It's not particularly revolutionary; it just presents the culmination of my house rules for OD&D (1974). The sole exception is the wealth system that I engineered especially for this release of the rules. In the near future, I plan to release a free supplement introducing more character races/classes and a few simple adventures.