sdesalas

This plugin allows your WordPress blog to output pages compressed in gzip 
format if a browser supports compression.
HTTP compression generally means a 60-80% REDUCTION in the size of your pages 
(broadband usage) as well as an INCREASE in download speeds of 3x to 4x.
To test if your blog is using compression use the following link:
http://ismyblogworking.com/
Check “Page GZip” on the right hand size. 
Check “Bandwidth saved by compression” on the left hand side.
NOTE: This plugin should not be used alongside WP Super Cache or WP Cache 
since those plugins are already implementing compression. Your blog 
will keep working but those plugins will stop caching new pages.
RECENT NEWS – 20 March 2010:
Its been reported by a user that there is a conflict 
using WP HTTP Compression together with Google Analytics Plugin (3.2.5). I’ll 
to look into this and release a patch for next release. 
Note that this conflict is NOT with Google Analytics itself but with 
the PLUGIN. Google Analytics scripts and stat collection have been tested 
and work fine with the WP HTTP Compression plugin.

WP HTTP Compression

This plugin allows your WordPress blog to output pages compressed in gzip format if a…

riotweb

About
This plugin will instantly speed up your WordPress website when the plugin is activated. 
Gzip is the most popular and effective compression method currently available and generally reduces the response size by about 70%!
Important 
This function changes your .htaccess file. In some cases this might result in a 500 error. If you’re not sure whether you can run Gzip ask your hosting company. 
The only way to fix this is to be able to edit the .htaccess file from outside WordPress (via FTP).
Gzip Checker 
NEW – You can now check if Gzip is enabled for your website. Go to “settings” and select the “Instant Gzip Compression” tab.

Instant Gzip Compression

Speed up your Wordpress website with this Gzip compression plugin.

WP HTTP Compression vs Instant Gzip Compression