Since I don't have any close friends that brew, I'm going to be the mentor sometime down the road. It's great blogs (like this one), message boards, books, and the one guy I met from a message board that are willing to share information with me. Thanks, NB.
The BN, BYO and my homebrew club are my greatest resources for learning. Oh, and now your blog.
John Palmer via "How to Brew". I flew solo (only books and the library) for the first 4 years of brewing before finding internet forums etc. for discussing brewing.
I was fortunate enough to have a couple of friends who worked for Northern Brewer. They not only mentored me, they got me into good beer in the first place!