http://www.insidescanlation.com/
Very extensive fan-made resource on scanlation and its history, chock full of great info. Includes a timeline of scanlation, in-depth articles on important online hubs and scanlation groups, background info on the ins and out of scanlation and various related issues, and more. TWC did an extensive review of the site and the info on it in 2010.
Fanlore’s scanlation article is a good and quick intro to the topic, by the way. For some longer reads on scanlation, here’s a list of academic articles that are definitely worth checking out as well. (Link goes to the work-in-progress bibliography of fan studies work that TWC and Fanhackers are working on. More on that one later. If you need access to any of the articles that are behind a paywall, try requesting a copy on Fanhackers.)