Receive e-mail when somebody writes your nickname in a post

[Lea Verou]

Today my boyfriend gave me this idea:
What if there was a hack that each time somebody wrote your nickname in a post you would receive an instant e-mail for that post as if you were subscribed to the thread?
That would be really useful I think (if it includes a turning-off option so that users with very common nicknames don't receive loads of e-mails).
However it would be VERY server-intensive the way I think about it. It would probably need to check every single word in every post that is made (well, those that are within the limits set for nicknames eg min characters) and look if it matces any of the nicknames that have the feature enabled. This way it's a server-killer as most of you can see.
Is there any way to make this more light for the server and is there someone that can make it or give me some guidelines of how to do it?
I think it's really worth the thinking, it seems very useful.