Chris Gates presentation from ToorconX has been posted on his blog: http://carnal0wnage.blogspot.com/2008/10/new-school-information-gathering.html . This is a great slide-deck. His presentation covers quite a few things from using Maltego through looking at meta data from published documents to discover user names, userids, and file paths. Much of this stuff is stuff you would never have to touch one of your client/target's website in order to discover.