If you use IRC, the #mysql channel on Freenode can be an excellent free resource for asking MySQL questions while you're working on something. Many MySQL engineers, support staff and former employees "hang out" there. Don't expect instant answers, but the crowd is generally helpful. They will, like Open Query does too, try to teach best practises and resolve underlying problems, and not only answer the narrow direct question.
On the same network, you will also find #mysql-dev which is Sun/MySQL's public channel for its own developers, and #mysql-university which is used for online informative sessions about MySQL internals.
For Drizzle, join the #drizzle channel on Freenode!