Microsoft may have come up with a way to cut down on spam. The Penny Black project (named for the idea from the 1800's that senders should pay for postage not the receivers) will make spammers pay for sending email by requiring each emailer to attach a small cryptographic puzzle to their emails. Since attaching this puzzle to the email will require computing time the spammer will have to invest in more equipment in order to be able to flood the system with millions of emails. Therefore spammer will "pay" for sending out huge numbers of emails because their amount of computing time would be huge. Our email programs would have puzzle solvers to interpet on incoming messages and attach the cryptographic puzzles to outgoing messages. The "cost" in computing time to individuals or legimate companies of sending out emails would be minimal.

The BBC has an article on this here.

There are a lot of ways to personally fight spam now. The best is to get a Yahoo or Hotmail account and let them worry about it. I like to use Outlook for email. To cope with spam I have set my rules wizard filter this way: After the message arrives: "where my name is not in the To box permanently delete the message and stop processing more rules." This gets about 90-95% of the spam. I use my Yahoo account as my email account of record.