Well, I'll kick off the new and hot. There have been a couple of references to Darwin websites. There are two in particular that are phenomenal resources. The first is Darwin Online (http://darwin-online.org.uk/), which is probably the best internet resource devoted to a single historical figure in existence. It has every one of his books in full text electronic format, as well as difficult to find and unpublished private papers and the like. Almost everything is available both in text format and as an image of the relevant editions. Every edition of the Origin is available, so if, for example, you want to look at the part of the third edition that added the summary of the evolution of historical thinking, it's there. One hint. The search functionality within a document kind of sucks. Once you are in a document, if you want to find a particular word or phrase, use the find function in your browser rather than the search function in the site.
The second is the Darwin Correspondence Project (http://www.darwinproject.ac.uk/), which has electronic full text access to much (though not all) of his correspondence. There are about 11 hard copy volumes or something at this point, so it's great to have it all online and searchable. He often discusses important issues about his theory in his correspondence, so it's really worth a look.