Just found this today and said, wow! I need this!
Simple plugin install, hit activate, and bam!
Permanently redirect all 404's to the main blog URL. The primary purpose is to salvage Google PageRank (TM) from missing pages.
WordPress › 404 Redirection WordPress Plugins
It seems to be interesting,
I install it for my blog. Thanks dear.
It should be good for redirecting users to the home page, but if a status code 404 is generated it will not pass PageRank to the home page. It takes a 301 status code to do that.
"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." -- Benjamin Franklin