Joining online survey panels can be a great way to earn that extra dough.
There are tons of different companies which will pay you to answer surveys for them. The only downside to this is you may not always qualify for certain surveys, which means it may take you a little while to accumulate enough points or money to cash-out. Most sites with have a minimum cash-out, usually ranging anywhere from $10 to $50. Although doing online surveys for cash can be kind of slow, if you are signed up to enough companies then it will all add up. I have made a list of all the survey sites that I use and have personal experience with. If you are not sure of the legitimacy of a website you may check out the Survey Police. They are an online directory which rate the top survey sites according to user votes. Very helpful in knowing which sites are scams and which are not.
Opinion Outpost is a site that will send you surveys which you fill out for points. Most range from 20-25 points per survey. When you are screened out of a survey you are given a chance to choose between sweepstakes entries and instant spins just for trying, which I think is a good feature.
Angus Reid Forum pays you cash or gives you entries into contests depending on the survey and you have a minimum cash-out of $50. Most surveys pay around $1-3 per survey.
Ipsos I-say is another points based survey site. Normally 30-90 points per survey and you get entries into contests as well. Even if you do not qualify for a survey you still get 5 points plus you get to play the poll predictor game, which is my favorite part.
GlobalTestMarket will either pay in points or sweepstakes entries. They usually send out a generous amount of surveys as well so if you don't qualify for some you are guaranteed to earn something. If you are screened out you still recieve sweepstakes entries.