Blackboard alternatives?

My school district is getting rid of Blackboard due to budget constraints next school year. I have spent the past three years building/tweaking the Blackboard aspect of my class (assessments, uploading power points and other class files, etc) and I am looking for a good alternative for the e-learning aspect of my class. It sounds like the district will be replacing Blackboard with Projectshare.org... Are there any other good, free alternatives out there? By the way I teach high school science.