When Businessweek.com asked readers over the summer to suggest the most promising companies run by entrepreneurs 25 or younger, more than 200 people responded. We've narrowed the suggestions to 25 finalists whose stories are told here. Please take a look and then vote, through Oct. 20, for the one you think is most promising. We'll announce the top five readers' picks on Oct. 27. Photographer: H. Armstrong Roberts/Getty Images
Note: Revenues are self-reported. To be considered, founders had to be aged 25 or under when the nomination period closed in late July.