Bitcoin wiki (https://en.bitcoin.it/wiki/Main_Page) is probably the best source of technical information about bitcoin protocol.
You can find etotheipi's diagrams there (e.g., https://en.bitcoin.it/w/images/en/7/70/Bitcoin_OpCheckSig_InDetail.png, https://en.bitcoin.it/w/images/en/9/9b/PubKeyToAddr.png).