Michael Thomas

404 errors are generally very ‘expensive’ on WP sites as they cause WP to run on every attempt, slowing 
down your site and causing additional load on your web hosting environment.
WP Speed 404 can either suppress or log and email any 404 errors affecting your site under wp-content, wp-admin and 
wp-includes (configurable).

WP Speed 404

WP Speed 404 can either suppress or log any 404 errors affecting your site under wp-content, wp-admin and wp-includes (configurable).

LoudSkyMedia

This simple plugin permanently redirects all 404’s to the main blog URL. There may be several reasons why you might want to do this, but the primary purpose is to siphon Google Page Rank (TM) from missing pages to the homepage.

404 Redirection

Permanently redirect all 404's to the main blog URL. The primary purpose is to salvage Google PageRank (TM) from missing pages.

WP Speed 404 vs 404 Redirection