Placing the power of controlling spam into the users hand is the heart of this Clickz article by Paul Soltoff. He supports placing complete control of spam into the users hands. While this approach individualizes what is and isn't spam, I think it requires a lot of work on the part of the user. Even if you create a giant list of what you determine to be spam, there will still be more.
Rick Bruner wrote about a company called Cloudmark the other day. Cloudmarks' approach creates a database of spam based upon users of Cloudmark. If a user deems something spam, it is entered into the "spamnet" database and determined to be spam for all. But, there is a drawback. One man's spam is another man's great deal on a mortgage.
There is no perfect solution yet but at least now, there are choices.
The solution I propose puts the power to block/filter email into the hands of consumers. Right now, that power lies with Webmasters, IT managers, spam cops, ISPs, and so forth, each of whom -- albeit with the best of intentions -- has developed independent sets of arbitrary rules on what constitutes spam. That sounds like well-intentioned censorship to me. Think of it this way: I may want to receive home mortgage email offers by the truckload because I happen to be in the market for a mortgage. You may not. Whether the offer screams "free" or "hot" or "click now" is irrelevant.