This following link can take you to a new guide on Project Based Learning. You can have a better idea, and ideas of projects in the iEARN website also listed below.
http://www.iearn.org/professional/project_based_learning.ppt#265,10,Eight Features of Project-Based Learning
http://www.iearn.org/projects go to the project´s list and get to know the project that best fits your students´needs.
I invite all of you to post your thoughts on PBL here.