I want to go on a religious missions trip to Tanzania. Whats a good organization to meet up with?

2 years ago I went to Burundi, Africa for 2 weeks and ever since I have been wanting to go back to Africa. While there we helped at an orphanage for a few days and traveled around the country holding church services and doing various prayer and evangelism stuff. Ever since that trip Tanzania has always been on my mind as a place to return to next. It seems as if my current cirstances will allow me to partake this adventure this coming February 2009 and my work has agreed to grant me the month off. I am a 27 yr old male and very spiritual minded individual and am planning on traveling alone right now. What would be a good organization to meet up with in Tanzania? I am open to places other than Tanzania, I just basically want to venture off and help for the month. Got another group outside of Tanzania feel free to let me know. Thanks!