Tools for spike traffic: what's out there?

Here's what I'm looking for. It should be a trivial service - something like a .JS or .GIF I can drop on to the pages of my site. When I start getting DIGG or REDDIT traffic, it should send a message to my email/phone/pager within 15 or 20 minutes, telling me that I'm getting nailed, and I should keep an eye on things. It should also tell me the URL I've got incoming from.

It'd be nice if it, or a second service, would cache the pages which are being nailed, and show me how to do a redirect to the cached pages for whatever software environment I'm on (i.e. auto-generate a .htaccess line for mod-rewrite, or the appropriate incantations for other configurations.)

And, just out of curiosity, why don't things like WordPress have an option to automatically generate a redirect to the Coral Cache version of pages when they get nailed?

Spike traffic is a really here-to-stay phenomena, and I don't understand why the only effective tool commonly recommended is "build a ton of overcapacity and let it sit idle the rest of the time."

There's got to be room for new approaches here.