*Science textbooks:
evolution, biology, genetics, geology (as it relates to evolution & interactions between organic & inorganic) ...
*Anthropology textbooks
*Some sci-fi + fantasy like Harry Potter, but haven't read anything like it recently
*Computer Science -- mostly computer language coding. Presently learning PHP & JavaScript. I have learned Java, C#, ASP.NET, & C++ so far, along with details of networking, database coding & queries, some data structures, & computer hardware basics.
*I collect books titled 'History of the Idea of Progress' - there are several versions. So far I have 1980, 2005, 2008, & 2012 versions. The 2005 version is titled 'Technology & American Society, but the concept is similar.