The point of each survey is to present you with a topic you're interested in and qualified to discuss for the benefit of the researcher. Surveys range in time required, from very short to quite long. Because researchers are looking for opinions only from certain segments of people, you may find you have to try a few surveys before you're qualified to give your opinion on one. Keep at it, and you'll eventually find one that's right up your alley.
Amazon gift cards and PayPal are obviously popular choices, so naturally like most sites MySurvey had those. These guys did not stop there though. At the time of writing (I double checked) they also offer various sweepstakes, gift cards to restaurants, you can donate to charities like UNICEF through them, they have iTune gift cards, their very own merchandising products and also Starbucks, Walmart and Tango gift cards among many more options!
Ipsos is a funny name for one of the oldest and largest global market research companies. They were founded in 1975 and if you follow US politics, you'll recognize them partnering often with Reuters to produce approval surveys of Congress, the President, and other notable figures. They're headquartered in Paris, France and publicly traded on the Paris Stock Exchange. They have revenues of over a billion dollars – Ipsos i-Say is just a small piece of their business.
IOCS is a not-for-profit research organization that conducts studies and experiments on shopping-related behavior – things like how we, as consumers, evaluate products, how we make the buying decisions, etc. Although the focus is mostly on shopping related behavior, some of their experiments and studies include broader areas of marketing, psychology, and economics.