http://mark.koli.ch/2009/04/howto-use-apache-mod-deflate-to-compress-web-content-obsessed-with-speed-of-kolichcommobi.html
http://httpd.apache.org/docs/2.0/mod/mod_deflate.html
http://www.cyberciti.biz/tips/speed-up-apache-20-web-access-or-downloads-with-mod_deflate.html

DeflateCompressionLevel 9
SetOutputFilter DEFLATE
BrowserMatch ^Mozilla/4 gzip-only-text/html
BrowserMatch \bMSIE !no-gzip !gzip-only-text/html
SetEnvIfNoCase Request_URI \.(?:gif|jpe?g|png|ico)$ no-gzip dont-vary
SetEnvIfNoCase Request_URI \.(?:exe|t?gz|zip|bz2|sit|rar)$ no-gzip dont-vary
SetEnvIfNoCase Request_URI \.pdf$ no-gzip dont-vary
SetEnvIfNoCase Request_URI \.avi$ no-gzip dont-vary
SetEnvIfNoCase Request_URI \.mov$ no-gzip dont-vary
SetEnvIfNoCase Request_URI \.mp3$ no-gzip dont-vary
SetEnvIfNoCase Request_URI \.mp4$ no-gzip dont-vary
SetEnvIfNoCase Request_URI \.rm$ no-gzip dont-vary
Header append Vary User-Agent env=!dont-vary

DeflateFilterNote ratio
LogFormat '"%r" %b (%{ratio}n%%) "%{User-agent}i"' deflate
CustomLog logs/deflate_log deflate