I implemented arithmetic coding during a student internship for Infra Design in the summer of 1993. I loved it, and agreed with David MacKay two years later in his introductory info-theory course at Cavendish TCM, when he described it as the only compression algorithm that deserved to be called such.
Here are a few open source implementations with accompanying tutorials -- Ian Holmes - 03 Sep 2006
- Bob Carpenter, Java, BSD
- Includes tutorial on PPM (finite-context predictive model) & thorough list of references