Ethernet is the ubiquitous network that connects our computers together, and is also rapidly finding many new areas of application. There was a really good article in EDN Magazine a few years ago describing the history and Evolution of Ethernet from the early days of 10 Mbps half duplex communications to the current 10 Gbps standards [1]. The article contains some really good pictures of the different signaling types in the form of eye diagrams and waveforms. This article was actually the first in a two part series, with the second part covering power over Ethernet, and wireless Ethernet options [2].
[1] Marsh, David. October 14, 2004. "Ethernet Keeps Pumping the Data." EDN Magazine.
[2] Marsh, David. November 11, 2004. "Power and Wireless Options Extend Ethernet's Reach." EDN Magazine.