Pysync has both a demonstration implementation of the rsync and related algorithms in pure Python, and a high speed librsync Python extension. The pure Python is not fast and is not optimized, however it does work and provides a simple implementation of the algorithm for reference and experimentation. It includes a combination of ideas taken from librsync, xdelta, and rsync. The librsync Python extension is less flexible and harder to understand, but is very fast.
xml_pickle performs serialization to an XML format with several properties not possessed by the standard pickle module, namely, the format is human-readable, the format supports validation of stored serialized objects, and the format may be parsed, manipulated, and objects imported, by languages other than Python,
python-fchksum is a module used to find checksums of files (or stdin). It supports md5, crc32, cksum, bsd-style sum, and sysv-style sum. The advantage of using fchksum over the Python md5 and zlib(.crc32) modules is both ease of use and speed. You only need to tell it the filename, and the work is done by C code.
Python-LZO provides Python bindings for the LZO data compression library. You can access the LZO library from your Python scripts thereby compressing ordinary Python strings. LZO is a portable lossless data compression library written in ANSI C. It offers pretty fast compression and *very* fast decompression. Decompression requires no memory. In addition there are slower compression levels achieving a quite competitive compression ratio while still decompressing at this very high speed.