I have been participating in online surveys for the last couple of years and have earned quite a generous amount as a result of my efforts. Surveys could be time consuming but depending on the site your on, potentially you could come out with a good compensation for taking in such activity! Consider this as a good sideline income though and don’t replace your day job with this. Here are some legitimate sites which I have received payment in the past and therefore could personally vouch for.
Pinecone research — Potentially has the biggest compensation for any survey sites in the internet but you must withstand two problems. First, to register you need to find a pinecone research logo placed anywhere in the web and secondly, survey invitations come in rather meekly.
zoompanel.com — Survey invitation frequency is a lot so you get to participate in as much surveys as you want. The only downside is that they currently offer no payments through paypal. The only rewards you get is to browse through their online catalog and redeem your points for anything you want from their catalog just as you meet the point requirement.
Myview.com — To date, I have made more money with Myview than with other survey sites in the internet! The compensation for taking on 20-30 minute surveys is not bad either! You get to be paid anywhere from US$3-5 for every survey you finish and best of all you get paid through paypal.
http://www.AWSurveys.com/HomeMain.cfm?RefID=chaddie01 — AW surveys is more of like a site review rather than a survey site. You get a couple of links per survey and you have to evaluate the site in one sentence. The great part is that you get to have a $25 bonus for signing up and they also pay through paypal.