Although I don't agree with these type of questions in job searching, depending on what field you going into employers do ask for Facebook or social media accounts before hiring. Some use that to determine you character, good judgment and whether or not you are likely to post embarrassing information that could harm the business's reputation (for example, the McDonald's employee who posted a picture of himself taking a bath in the McDonald's dish washing basins.). I am not sure if it is legal but it happens.