I came across a good site today while I was reading the stagecraft mailing list and surfing the net on related topics. It is: http://www.efunda.com/processes/processes_home/process.cfm
I found it in a search for information on cnc milling, but they have alot of introductory information on alot of metalworking processes. Unfortunately, you can get into the site through the backdoor via yahoo, but surfing around the site outside of the area you enter in requires a password. On the positive side, membership is economical. 6 a month, 60 a year or 36 for students. If I get a membership, I will keep you posted, or if someone has used the service let me know.
And by the way don't try this at home: