This is not very comfort zone stretching, but you might want to the 5 tibetan rites for 30 days in a row; here is a sales pitch
The Five Tibetan Rites: Chet Day's Annotated Version of Peter Kelder's Classic Tibetan Rejuvenation Rites, but you can also find them here
LifeEvents.org: 5 Tibetans Energy Rejuvenation Exercises . Really awesome exercises.
The other thing that may be cool is to learn to speak a new language (shoot for fluently) in 30 days. Great resource for this may be
Welcome to Michel Thomas , but for the rest you may want to investigate some ways to get the language down really fast (like getting the basics down through Michel Thomas, then listening to audio tapes you are really interested in that language, then finding people to communicate with, writing on internet forums in that language, learning a new simple skill that you are interested in that language, etc..).
Edit: I see that 'kat' did the same suggestion