Daily deals sites are Web sites that provide various deals that are only available for a limited time, usually throughout the day and sometimes even less time than that such as maybe hourly deals. These are also usually very good deals. They're not always the greatest though so do some research prior to making your purchase. Usually doing a quick search on swagbucks or Amazon.com will help you figure out if it's a decent deal or not.
Also, sites such as these sometimes promote free things to try and help get more users to their sites so sign up for their daily newsletters so you can see if they have anything special going on. Just make a separate file in your email account to have those emails go to so they don't flood your inbox.
Here's a list of some of the sites available. Feel free to leave a comment below with others not listed: