There has been a big push recently education towards project based learning. Students are given a project to complete and are given near free reign to accomplish their goal. The can work individually or cooperatively and the teacher is there merely to guide them. The student becomes in charge of their own learning and education.
A piece of free software that I find meets this criteria perfectly is called a wiki. A wiki "is a website that allows the creation and editing of any number of interlinked web pages via a web browser using a simplified markup language or a WYSIWYG text editor" (Wikipedia 2011). What this means simply is that a wiki is a webpage that users can edit easily. The wiki is usually divided into categories and is easily searchable. This could be applied in a number of ways in the classroom. Take history for example. The teacher divides the class into groups. He or she then assigns the students a project on one battle of the Texas Revolution. One their portion is done, they must visit the other groups page and check for errors. Any errors are corrected and the changes are tracked for the teacher to see. The students are teaching themselves. Below is a real world example of a wiki being used in the classroom.
If you'd like more information on building a wiki for your class, please watch this:
YouTube (2009). How to Build An Educational Wiki. Available from: http://youtu.be/7q90qzQnfsI
YouTube (2009). Using Wikis in the Classroom. Available from: http://youtu.be/1pR5yogCmkA
Wiki. In Wikipedia. Retrieved October 23, 2011, from http://en.wikipedia.org/wiki/Wiki