I have found a great new tool in the war on spam email. It's called sneakemail. Essentially what it does is allow you to create an unlimited number of email aliases. An email alias is an address that just forwards to your 'real' email address.
So if someone emails your sneakemail.com address, it comes to your real email address. Then, if you reply, the email gets “masked” by sneakemail.com, so your real address is never exposed; the reply actually comes from your email alias.
Let's say you buy something online from Bob's Book Store, and they require an email address in order to make a purchase. If you give your real email address, and Bob's Book Store starts spamming you, or selling your email address to 3rd party spammers, it will be difficult for you to get rid of tho spammer(s). Even if you do, it's likely your address has gotten into a database and/or sold to other spammers, so the process continues.
But if you use an alias, and if you're very specific about how you use it (i.e. use one alias only for Bob's Book Store), then you can more easily track down the spammer. If you only give the email address to one entity and you get spam at that address, it has to be them, right? Or if you don't really feel like hunting them down but just want to stop receiving the spam.. well just delete the email alias.
Slight downside: the aliases are randomized, so you can't choose an easily readable alias. They're more like adfa342dfqY@sneakemail.com. But when you get an account you can manage your aliases by nicknames so it's not really that big of a deal. Check them out, there's a lot of other cool filtering/blocking features built in. Oh and it's free. :-]