After doing a daily challenge in 2011, I would highly recommend them as a way to get into the habit of blogging and developing a body of work.
For 2012, WordPress is encouraging 365 challenges. It’s been interesting to reading all the ideas people have for a 365 challenge this year. Take a look and see if it tickles your fancy.
The 2011 Daily Post prompts are still out there.
Interested in other challenges?
KittyHere is doing the Six Word Fridays. Topics are posted weekly and the challenge is to do a six word sentence or several six word sentences or even a poem with six words per line.
judithhb is participating in a Six Word Saturday. CallMeCate is using a random number chooser to visit blogs each week and encourages participants to visit others as well.
Enjoy!
A Daily Life 
January 8, 2012 at 8:13 pm
All you have to do is Blog surf a bit to find all kinds of challenges and prompts.
January 9, 2012 at 9:38 pm
I read your answer and had to laugh at myself. It never occurred to me to do that and I’m the queen of Internet surfing! Excellent suggestion – thank you!