Since I make a good part of my living by teaching, I'm very interested in how people learn, and in "cognition" in general. In this vein, a friend recently pointed me to Howard Gardner's Multiple Intelligence Theory. Here is another web page relevant to this.
I also use some NLP (Neuro-Linguistic Programming) principles in my work, though I'm far from the fanatic a lot of NLPers seem to be. The net is lousy with NLP-related stuff; any search engine can find it for you, and I have no idea what to recommend and what not to, so I'll just leave it at that.
I base a lot of my business practices on things I found in a book by Don Lancaster. Don was one of the pioneers of the golden age of hobby electronics (early 70s to early 80s), is a widely-read columnist in several current magazines, and his TTL Cookbook and CMOS Cookbook still sell briskly. If you're running your own business, or would like to, visit his web page and buy his book, The Incredible Secret Money Machine.