SEOClerks - The largest SEO Marketplace on the planet. - SEOClerks
Amazon Mechanical Turk - The online market place for work.
Picoworkers - Earn money from doing short, easy tasks similar to Microworkers. Picoworkers is the best alternative to Microworkers I ever find.
SerpClix - SerpClix is a click exchange network used to send more real clicks to your Google SERP. You can click to earn money or buy clicks to rank higher on Google.
Bitfortip - Tip Bitcoins as an incentive | Earn Bitcoins for being helpful
Fiverr - One marketplace, millions of professional services.