The history of the telegraph is a somewhat understudied topic on the Internet. However, this website looks pretty good, and includes a bunch of links. Even in print, it has not attracted as much first rate writing as the radio. There is a great chapter on Britain's world network and the use of the telegraph for imperial communication in Headrick, Daniel. The Tools of Empire: Technology and European Imperialism in the Nineteenth Century. Oxford, UK: Oxford University Press, 1981. If you're curious about the stuff on new reporting through the telegraph, there is a whole book on that topic: Blondheim, Menahem. News over the Wires - the Telegraph and the Flow of Public Information in America 1884 - 1897. Cambridge, MA: Harvard University Press, 1994. On the parallel topic of the US postal system, the best recent work is John, Richard R. Spreading the News: The American Postal System from Franklin to Morse, Harvard University Press, 1995.

Now the history of the internet, on the other hand, is rather a popular internet topic. Much, much more of this focuses on the technological details than on the social context. The classic resource of this kind, and your best source for reliable dates, is Hobbes' Internet Timeline. The Computer History Museum includes a nicely presented timeline on its site. PBS did a series on the Internet, called Nerds 2.01 (a sequel to Triumph of the Nerds, which they based on Accidental Empires and had Cringely host). Its website is nicely presented and covers the right ground, but doesn't go very deep. Aside from that, there's a lot of good stuff mixed with a lot more rubbish -- so be careful before trusting a random site.

One history, Netizens: On the History and Impact of Usenet and the Internet is available in print and on-line in plain text. It's a mixture of fairly reliable history and fairly out there hacker ideology (check out the appendix).

You have two of the best readings already -- the Abbate book is well worth reading, though except for the chapter you were assigned it sticks more to the protocols and networks themselves and how they came to be the way they were than with what people actually did with the network. It's well written and carefully researched.

There is as yet no great scholarly history of the web, as opposed to the Internet itself. A good popular book, full of details and with a refreshing British flavour to it is James Gilles & Robet Calliau, How the Web was Born, Oxford University Press, 2000. This has nice summaries of the various strands we covered (timesharing, packet switching, videotext), but focuses mostly on the creation of the web at CERN, where both authors worked. Tim Berners-Lee tells his own story in the much less meaty Weaving the Web (Harper Collins, 1999).