Online box office tracking firm Box Office Mojo has been acquired by IMDb.com Inc., a subsidiary of Amazon.com. The Burbank-based Box Office Mojo will remain as a standalone business providing analysis and tracking of the box office revenues of feature films. IMDb is committed to furthering the Box Office Mojo brand and building upon the success since it was founded nine years ago, the company said. This is the second San Fernando Valley acquisition by IMDb this year. In January, the company purchased Without A Box Inc., a Studio City-based online site that pairs independent filmmakers with festivals and their audiences.