The forums are a great resource, but I also scour the knowledge base articles, training videos, and reaching out via Twitter. As far as IRL interaction, the Tableau User Group meetings are really helpful as well. I really try to engage in as many ways as possible, and the support of the community has been wonderful!
Right here. The forum.
Sometimes I google "Tableau <whatever it is I want to find> ...", and invariably the links I get are to forum threads anyway.