Like most people, I get really annoyed by spam. Unlike most people, I have access to a mail server that lets me give myself as many e-mail addresses as I want. For several years, now, every time I've registered for a new service or signed up for an e-mail list or had to give a company my e-mail address, I've given out a unique address keyed to that company, web site, or what-have-you. That way, when I start getting spam, I can tell where the spammer got the address.
I think I'm starting to see an interesting pattern.
Most of the spam does not seem to be coming from companies that sell e-mail lists. Now, I need to qualify that a bit: I'm usually very careful to look for and un-check any "send me e-mail" boxes when I register, so that might have something to do with it -- some companies might figure if I'm willing to get e-mail from them, I'm willing to get it from other people too, and pass the address along.
Instead, most spam seems to come from two sources. One is e-mail lists. I'm on several e-mail lists. Those lists usually archive their messages on a web site. Spammers seem to be either going through the web sites trolling for addresses or subscribing to the more active lists and collecting them that way.
The other source is people pulling addresses out of the WHOIS database. This source won't affect people who haven't registered a domain name. (If you don't know what that is, don't worry about it -- you won't get spam from this source.)
Bottom line: what's it all mean for you? If I'm right about this pattern, you might be able to avoid most of your spam by using a google, hotmail or yahoo address when subscribing to mailing lists, but you can safely use your regular address when registering with most companies or corresponding with friends. The nice thing about this approach is when you start getting too much spam, just abandon your old list address, create a new one, and re-subscribe.