How to Use Pobox addresses to Reduce Spam
Well, obviously, the first thing I always suggest is Pobox's awesome spam protection, but you can also use multiple email addresses to help stem the tide of spam. All Pobox accounts include at least 3 addresses, which all deliver to the same place.
The first address is your protected address. This address is your precious. You only give it to people you know in real life, and trust. This address is for personal correspondence ONLY. No matter how much you like a company, or trust a shopkeeper, never give your protected address to any company -- sooner or later, it will get sold. (Also, don't make your protected address something like email@example.com -- any very common first name or three or four letter combination will get spammed by dictionary attacks, no matter how careful you are.)
Then, the other two addresses can be rotated. If you start getting too much spam to one of them, you can deactivate it for a few weeks. Then, turn it back on. Or switch it to a new address!
Even better, get your own domain, and use AllMail to send mail sent to any address at your domain (except for ones that you specifically want to send elsewhere) to one address. Pobox spam protection lets you see which address a piece of spam was sent to, so if you see that an address at your domain is getting too much spam, you can deactivate it, so messages to that address will bounce. Spammers usually get the hint pretty quickly that an address just doesn't work anymore.