I recently joined and submitted DNA to the personal genome service, 23andme. I'll post more about what I've found later. Much of it shows no direct relevance to ADD/ADHD, but some of the findings are significant.
For now, I would like to note that I have become very interested in my DNA. I know my DNA! That's crazy. Most people don't. It's understandably scary. But I haven't honestly learned that much about myself from their results. The most important finding for me has been that I process caffeine slowly, which means that having 2-3 cups a day increases my risk of heart disease. That's immediately useful information.
One part of 23andme is ancestry. So, just for fun, I want to share this. They conclude that I am most genetically similar to Northern Europeans:
Using Google Docs, I also made a chart of it from an admixture proportions tool at gedmatch.com:
And here is a more detailed look from 23andme. I'm the green marker.