Justin Fletcher has recently started posting some very in-depth and interesting articles on his website detailing various developments within RISC OS during his time as a developer for RISCOS Ltd. The articles cover a range of topics and offer a unique insight into some of the inner workings of both RISC OS and RISCOS Ltd. as well as some other RISC OS related topics, such as the RISC OS ports of the games Doom, Heretic and Hexen.
 
Currently, Justin is posting an article each weekday (and has been since the beginning of December).
 
You can take a look at the articles on Justin's website.