Dewey is again hosting a 24-hour readathon, this one to be held on October 18 starting at 8 am EST. You can sign up and/or get more information here. There will again be mini-challenges and prizes, along with a great opportunity to catch up on some of your reading and to check out other blogs. You can sign up as a reader, a cheerleader, or both.
If you've never been a part of this before, I highly recommend it -- I participated last time and it was great (although I conked out and so didn't make it the full 24 hours). Check out the FAQ's on Dewey's blog to find out more. You can also see what the mini-challenges were about by clicking "readathon" from my list of labels -- I only participated in a few but it will give you a general idea.