StumbleUpon is a social discovery engine where users can browse interests-based, user-rated web content. In 2009, the most stumbled items included a list of viral internet things, a summary of life in bottles, and rare color photos from the FSA-OWI archive. While Stumbling can expose users to new audiences and promote credible, innovative content, it is also a time waster with little user interaction and content is difficult to control since ratings are user-based.