Two social media sites, Reddit and StumbleUpon, can drive large amounts of traffic but dislike overt marketing. Reddit has over 20 million users and popular posts can receive hundreds of thousands of views within 48 hours. StumbleUpon has over 20 million registered users and while traffic bursts are smaller, content can continue receiving hundreds of daily views for months. To succeed, content on both sites must be targeted towards users' interests and not appear as obvious marketing.