1. DevelopMentors Bootcamps. The ones that run 10-12 hours a day. Especially if you get somebody like Fritz Onion. HARDCORE!
2. Nothing teaches you a product like investing your own time in making it do things you want to do. I'm sort of teaching myself InfoPath as an alternative to writing ASP.NET.
3. Writing a book. You know, you may feel so totally at one with something that you say "oh yeah, I could write a book about that." Go ahead. I dare you. I (breaking the rules of protocol and skipping over the single and double dog dares) TRIPLE DOG DARE you
to. You'll learn way more than ever wanted to know.