There are some more active things you can do.
1) Create a separate email for spam. I have my firstname.lastname@example.org address. I use that for any web forms I need to fill out. Then treat that mail very suspiciously (route it to a separate folder if it makes it through the spam filters).
2) All my mail gets spam-filtered three times before I see it (first by Eudora Internet Mail Server's black list, then by Spam Assassin, then finally by Mail.app's Baynesian filter. Of the 50+ spams I get a day, maybe 1 or 2 get through.
3) Bounce any spams that get through. Some spammers use a real return address to know which emails bounce and which get replies (to make their lists better). If you bounce the spams you get (Mail.app does this for you with the click of a button), you may be able to reduce your exposure.