JordiPlana

This plugin hooks the normal WordPress workflow in order to determine if the request is processing will cause a 404 HTTP error. In that case it prevents WordPress to do any other processing and sends the user to the page defined in the plugin options.
A working and simple solution.
For more information about this plugin you can check <a href="http://jordiplana.com/404-simple-redirect-plugin-for-wordpress" title="404 Simple Redirect Plugin for WordPress" rel="nofollow ugc">the official page</a>.

404 Simple Redirect

This plugin hooks the normal Wordpress workflow in order to determine if the request is processing will cause a 404 HTTP error.

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 browser supports compression. HTTP compression generally means …

404 Simple Redirect vs WP HTTP Compression