Smarter 404 was inspired by smart 404, however my changes are made at the controller and not the view support for 2.x was added, seo and non seo urls are supported and it now works for any theme.

what it does:

What it does basically instead of showing a 404 Page it searches the URL keyword on your own website.
Example:
if you go to yoursite.com/car (page doesn't exist)
instead of showing a 404 page its going to show you all the products on my website that have the word car in them.