Estrella Daura. I had never heard of it before, but low and behold, it actually tasted like beer. I'll be purchasing this for my next beer required event. Here's where to get it in NYC.
There are a few other gluten free beers available. Two of the most common are Bard's and Redbridge. They are fine. Daura is better.
I also just read this post by Gluten Is My Bitch. Looks like there are three other contenders. Have you tried any of these beers? Thoughts?