Alcoholics Anonymous is a worldwide network of support groups. It is, as the title suggests, completely anonymous, and very helpful to millions of recovering and struggling alcoholics. You've probably seen in a movie or a tv show the stereotypical solemn, stern, AA meeting. In truth, every AA meeting is different. In general, they can be quite warm and welcoming, and they leave you with a feeling of peace . Here's a link to the madison area AA website: http://www.area75.org/.
Narcotics Anonymous is very similar to AA, but with more of a focus on street drugs. Both groups however, are very conducive to recovery no matter what the drug of choice is. Although, there are more AA than NA meetings to go to. However, some people find NA meetings to be more comfortable, so here's a link for madison area NA: http://www.wisconsinna.org/BASC.asp. The AA website does provide more general information about the program and the twelve steps, and since the twelve steps are the main focus of both groups, you might want to take a look at the AA website for more info.