Make Love Not Spam campaign
The idea being that it will bump up the bandwidth (traffic) charges for the spammers or make their web sites slow and unresponsive.
Although at first glance this seem like fighting back at spammers and incurring 'them' additional cost it is not to be recommended because:
1. If the spammers are selling illegal products / services there is a good chance that they are using stolen credit card details - so it will not cost them at all!
2. Most ISP's host multiple sites on a single server - so hitting their site could severely impact other sites that were innocently hosted on the same server or network.
3. Using the screen saver may be illegal or against the Acceptable Usage Policy of many ISP's because it is similar to a DDos (distributed denial of service) attack.
So we would not recommend it - instead tell all your friends / colleagues to visit: http://www.spamhelp.co.uk for all the best anti-spam advice!