BuddyPress.org

If you know a bit of php, I’d try Prelovac’s WordPress Plugins. Actually, even if you don’t konw PHP, I’d get a php book and this book and WordPress Complete 2.7.

You could also just learn wordpress-specific php online. Read up on template tags, loops, functions. Again php is helpful to understand how all this functions. Don’t worry about MySQL.

Not sure what to do about BP as there is no real book that covers 1.2, but the Dummies book should explain the concepts.