It may have slowed up a little recently in regards to question and answer regarding a lot of the more in depth techniques and tactics, but if you search back even a year or 2, there are a tonne of valuable threads that have great stuff.

Nothing substitutes a good trainer if you're thinking of turning pro, or already fighting pro,,,, but if you can see any holes in your game or tips on fighting against certain style opponents, there is enough knowledgable people to give you a lot of food for thought.