I have a problem with fighting Spam with Spam. It's not the right answer. While our motives and intentions might be altruistic, there is a possibility, however slight, that such a function might return some legitimate email addresses. If it does, that person gets spam, and has NO idea why. What if that address happens to be a 12 year old girl, receiving email about viagra and penis enlargement?
No, I'm sorry, but I just don't think this is the answer. Spam services will just find some way of fighting it, and we would just have more problems on our hands.
The way to stop spam, if it's to be done by us individual users, is to only use your email address for "legitimate" sites that you trust. Don't put your email address out there for spiders to pick up. Don't ever respond to spam, even to "remove me from your email list." All that does is confirm your email address. Don't "send this email to 10 friends," and discourage any family or friend that sends stuff to you.
I'm not sure such a script is going to help at all, and if anything, a long script that generates a bunch of fake emails is just going to make my pages take longer to load.