Having said all of that, I don't plan to join any reading challenges but there are some that look quite appealing. So, I'm unofficially keeping up with them, if you will. If you're so inclined, do check out the following...
2013 Middle East Reading Challenge
Dive into Poetry Challenge 2013
7 Continents, 7 Billion People, 7 Books Reading Challenge 2013
Nerdy Nonfiction Reading Challenge 2013
Books: Passports to the World 2013 Challenge
Also, here are some books on my radar for 2013...