One of my favorite groups (non organizing and productivity related of course) is the National Association of Women Business Owners (NAWBO.) I have been a member for a number of years.
I have mentioned before how making time for rejuvenation and recharging batteries is so important. NAWBO is that for me. I go to meetings and meet energetic business owners and listen to great programs. I almost always have a great idea that I'm formulating as I drive home that one time a month.
I am now humbled that they selected me as one of their national spotlight members! You can see more here: http://nawbo.org/spotlight.cfm?mid=14
What do you do to recharge? What groups do you belong to that have helped you enhance your business?