A couple of useful sites that I've run across:
Want to read but don't want to register? Fear no more and go to Bugmenot.com where they'll give you a handy login and password.
Want to have mail delivered to you but no spam? Again hold your horses and visit Mailinator. When asked for an e-mail, all you have to do is type in email@example.com and instantly a mailbox is created. Now you enter that at Mailinator, take your e-mail, the mailbox vanishes and voilà! No spam, no hassle.