I don't think you need specialized language for different server errors. 404 errors should be unique, sure.

But this is the best thing I've ever done with server errors:

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An error is the best way to a lose a customer. But with this method you're giving the customer a very easy way to report the error and feel like they're being taken care of.

I'd spend extra time with your error reporting mechanism too. If you can gather the stack trace and error message that'll help. But it's going to help even more if you can put the error into context. So gather things like form post data at the time of the error, or session variables, or anything else that'll help you diagnose the problem. Ideally you shouldn't have to ask what this person was doing before the error.

This is also very effective at lighting a fire under your butt, so to speak. When customers request that you fix the problem and notify them when it's resolved, then suddenly these errors have an even greater sense of urgency. You will naturally then spend more time making sure these errors don't happen in the first place. At least that's the effect it had on me.