Free electronic books for download/browsing

General books:

• Gutenberg Project
• eBooks@Adelaide
• manybooks.net (based on Gutenberg Project(?) offering multiple download formats)
• etext archives
• UPenn Online Books
• Wikibooks
• The Open Library
• International Children's Digital Library

There are various sites listing available for free technical books:

• Free Tech Books
• Computer Books
• Programming language theory texts online
• Textbooks in Mathematics
• CiteSeer Scinetific Literature Digital Library
• Networked Computer Science Technical Reference Library
• Directory of Open Access Journals