I am an avid user of Swagbucks. In fact, it paid for most of my children's Christmas presents!
Swagbucks is a rewards site. Users earn "swagbucks" for participating in online activities, many of which you would perform online anyway. For example, the site has its own search engine. If you use it throughout the day, you will be randomly rewarded with swagbucks. You can also earn this "currency" for taking surveys, watching videos, and even playing games.
You can then redeem your Swagbucks for gift cards! My favorite options are gift cards for PayPal and Amazon. I do not put a lot of time or energy into the site, but I can generally earn the equivalent of $1 or $2 per day (sometimes more, depending on if nCrave is working for me!).
If you are new to the site, try watching Swagbucks TV and running the mobile app. nCrave activities are great, but they work inconsistently for me. Also, the surveys can help you earn a lot, but you have to be patient with them. You will not qualify for every opportunity.