The brainchild of Arlee Bird, at Tossing it Out, the A to Z Writing Challenge basically requires bloggers to put up 26 posts in 26 days based on 26 letters of the alphabet, one post beginning with each letter during the month of April, with Sundays off for good behavior. The challenge garnered 1300 participants last year, which led to thousands of blog visits for each participant. All categories of blogging welcome, as long as it has genuine content, and is not pure advertisement. Check out the website for more details.