I finally got a mailblocks account. World of difference. It is 100% effective in stopping spam, and in the two days I have had the account it has stopped roughly one spam every minute. I was getting over 3000 spams a day.
I now get none. I've decided to settle on firstname.lastname@example.org as my final real email address, though a lot of the others i've used are forwarded to go through the mailblocks system.
Try sending me an email and see how it works. I am quite happy with the product.