Really? There is such a thing that doesn't result in spam in my inbox? - Laura Norvig from iPod

This one doesn't send invites, you just need to check the site. I've never gotten spam from any of the legit ones, but it's tricky weeding out the duds. - Headless Gnad Kicker

Harris Poll is awesome. They only send survey emails (though they changed their system to screen out people who don't qualify for surveys, so I get to do fewer). I've also seen their surveys on the news a few times. - Heather