This challenge is pretty simple - commit to taking at least one photo every day for a full year. In some of them, you put them on a blog. Some you tag in a group like Flickr. Some have a topic, like a color or a subject (the self-portrait one comes to mind). And I'm sure some people just do it, without rules or public disclosure.
I've thought about doing one starting in the days before our big move - say, Nov. 1, 2009 - Oct. 31, 2010. I think it might be fun to have the first year of our new life out west documented.
Have you ever done a 365 challenge? If so, would you recommend it? What did you do with all your photos when your year is over?