Brainfart regarding Online-game-distribution-services

I’m trying to find articles pertaining the rise and development of such services as Steam and (to a lesser extent) Direct2Drive, and any online-game-downloading services. Problem is, my google-sense isn’t letting me make searches that yield anything useful. Any help, maybe even a pointer to a successful google search?

Founded in 2004, Leakfree.org became one of the first online communities dedicated to Valve’s Source engine development. It is more famously known for the formation of Black Mesa: Source under the 'Leakfree Modification Team' handle in September 2004.