I tried to trigger a 404 on your site hoping I could see one in action (and maybe see an example of the scripting) but you don't appear to be using it yourself?
You probably should offer a bit more information. After all, you're targeting this at technical users, the barrier for entry doesn't have to be that low. Particularly since the service you're offering is "trust me to redirect your users with javascript whenever your site messes up."
Agreed - I can't believe I forgot to make one for myself (embarrassing) - will be adding one later this evening.
I also agree I need to add more information. The javascript isn't redirecting at all though - just dynamically loading the page in the static error page.
You probably should offer a bit more information. After all, you're targeting this at technical users, the barrier for entry doesn't have to be that low. Particularly since the service you're offering is "trust me to redirect your users with javascript whenever your site messes up."