Over the last several years, I've run across many blogs talking about the Holidailies in December, and last year, I finally figured out that they referred to a writing meme, of sorts. Members commit to posting at least daily from December 7th – January 6th. You can register at the Holidailies site, either as a portal member, which means that you'll be posting excerpts to their main page, or an at-home member, which means you'll be writing, but not posting excerpte, or a reader, which means you commit to surfing blogs and highlighting the entries you think should be shared.
I'm participating again this year, and am really looking forward to it. My blogging has been unfocussed lately, so I think I really need a “project” to get me back on track.
They're capping portal members at 160, so if you haven't registered yet, consider doing so now.