One spam-fighting option I've never tried is a temporary email address. There are a number of similar services out there, but 10 Minute Mail
appears to be amongst the most simple (which is a good thing). Simply visit the site and click the provided link, and you're given an email address that is valid for the next 10 minutes. Use that temporary email address to register at those pesky sites that want you to give up your email address privacy for ever and ever in exchange for testing out their service. As you receive replies to the address, such as registration links or whatever, you are able to actually interact and reply yourself using the site, but only for the given 10 minutes. If you think you're running out of time, there's a link to get an extra 10 minutes. This is useful for those sites that take their time getting your registration link to you.
My only issue with this service is that it's extremely obvious what you're doing - the email addresses it provides look like this: email@example.com. It might be nice if they provided a different domain name for the email addresses they give out. Just a thought.
Overall, 10 Minute Mail works as advertised, and you can't argue with that.