A relatively new addition to the assortment of free online courses is Saylor.org. Saylor offers a wide variety of free curricula in subjects like English, chemistry, biology, business administration, mathematics, and art history. Although Saylor isn't accredited, it's possible to get a certificate from them after completing one of their programs of study, or individual courses. Three of their courses have been approved for college credit by the NCCRS:
Business Law and Ethics
Introduction to Western Political Thought
You have to take a proctorerd exam in order to get the college credit. However, you have a choice between using ProctorU for a $25 fee or choosing yoir own proctor, such as a librarian. Also, Saylor is in the process of getting more of their courses approved for college credit, meaning that this could soon be a major option for a low cost education.