Symbol Ranking has been common computing folklore for ages, Peter Fenwick gave the first modern treatment and implementation subsequently improved by Matt Mahoney for example by adding a secondary arithmetic compression stage. I added a few ideas of my own, rewrote it in C in a way easily embeddable to other programs to compress e.g. network connections and database logging.
This compression library, SR3C, hits the front where one either has to consume more memory or cycles to compress better. The compression is slightly faster to gzip -7, but results in ~11% smaller data. bzip2 -2 compresses slightly better than SR3C, but takes almost three times as long and is not on-line.
Matt Mahoney made a version whose command line interface compiles on Windows and benchmarked it as well. Both versions of SR3C are published under the MIT license.