In my asp.net applications, I\'ve typically used the Application_Error global event handler to log the error and redirect the user to a user-friendly error page.
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Elmah is a fantastic project and we use it for all of our ASP.NET applications. Not only does it log unhandled errors for you, it grabs the entire original page that the user saw, which contains a lot of detail for you.
It has email support, RSS feeds (both itemized and digest) and has an attractive console.
For 3 lines in config and a dll reference, I'd say that's a slam dunk.