There's a few users currently abusing my company's site via Yahoo Pipes (in the form of a few hundred thousand malformed requests per week). We're a decently-ra

There's a few users currently abusing my company's site via Yahoo Pipes (in the form of a few hundred thousand malformed requests per week). We're a decently-ranked startup (top 2k alexa) and the requests don't really hurt us, but they're screwing with our error reporting and stats. It's possible to "block" them by looking for a special HTTP header and conditionally matching their Yahoo Pipes user ID, but it'd be nice if the Pipes team actually took abuse seriously. They essentially told us they couldn't do anything when we submitted an abuse complaint. :(