BuzzAgent

BuzzAgent is a site where you link your social media accounts and take surveys to try to qualify for free samples that they call campaigns. 
When BuzzAgent thinks they have found a campaign that fits you, they will send you an invite which you have to accept or deny. The campaigns always have great full size samples that you must try and review in order to be selected for future campaigns. They also have specific instructions on where and how to review your products. 
This site also has something called a BuzzScore that can go up and down by completing (or not completing) tasks, taking surveys and linking social media accounts or blogs. While it is good to have a decent BuzzScore, do not worry if it looks low to you, if you fit a campaign they will offer it to you regardless of a lower score.
TIP: Be patient with this site. It takes time to get accepted for new campaigns and it is important to keep your profile current.