mod_gzip is an Internet Content Acceleration module for the popular
Apache Web Server. 

mod_gzip uses the well established and publicly available IETF
Content-Encoding standards in conjunction with publicy available GZIP
compression libraries such as ZLIB to deliver dynamically compressed
content 'on the fly' to any browser or user-agent that is capable of
receiving it.

This is the updated mod_gzip for apache version 2.0 and above.
It has better compression and better logging than the builtin module
mod_deflate.