The Internet History Sourcebooks Project is a collection of public domain and copy-permitted historical texts presented cleanly (without advertising or excessive layout) for educational use.

Insane obsessive list of Neil Young covers with amusing commentary

contains bunches and bunches of descriptions including stuff like bulgarian apple ][ clones

collection of photos and other id information for all sorts of north american bugs. can request bug id.

large collection of, often illustrated, articles on every imaginable mathematical topic

Comprehensive history with imagery on just about all surface tests, exhaustive FAQ, articles.

Many excellent long articles on Punic Wars, Alexander, Persia, Rome, archeological finds relating to the Teuteburg forest battle and so on - refs to available evidence and chunky quotes of primary sources

Writings on a number of technical topics, _exhaustive_ histories of various aircraft in Air Vectors section

Brief writings on topics ranging from engineering, maths, physics to history and the classics. Ancient greek lesson for reading Euclid in original included

collection of archived USENET posts on a variety of topics. Henry Spencer's posts in Space are interesting