A couple of years ago, I completed the A-Z in April blogging challenge. You blog for 6 days a week (Sundays off!), draw your theme from a different letter a day, and work through the alphabet. I had a great time and met quite a lot of great bloggers doing it, many of whose blogs I still read. I haven't become someone who does it every year though, and at the moment I'm quite glad not to have that pressure of daily blogging. You also really have to commit to visiting others' blogs which is, of course, a pleasure and often a delight, but does take up time.
Some of the blogs that I read regularly are doing it though. Perhaps you'd like to go and visit them and give them a cheer?
Writer DJ Kirkby's A-Z has so far included short fiction and information drawn from her writing and her day job as a midwife trainer.
Maria at First Draft Cafe is a writer taking writing as her A-Z theme. She's been sharing tips and advice, and the occasional nugget from her WIP.
Rosalind Adam is Writing in the Rain features a unique A-Z. She's doing a song title and lyrics from each of four decades: the 60s, 70s, 80s and 90s. It's such fun!
For more A-Z blogs (there's a massive list of all those signed up), visit the challenge's online home.