Computer science and engineering books: http://www.freetechbooks.com/
Programming language theory texts: http://homepages.cwi.nl/~atanasso/ref
Textbooks in mathematics: http://www.geocities.com/alex_stef/mylist.html
Scientific literature digital library: http://citeseer.ist.psu.edu/
Computer science journals: http://www.doaj.org/ljbs?cpid=114
Thinking in Java, Thinking in C++, and Thinking in Patterns: http://mindview.net/Books/DownloadSites