Microsoft Office is sold as a bundle of computer software, including Word, Excel, and PowerPoint.

FORBES: Product Bundling is a Smart Strategy -- But There's a Catch

In computer superstores, 60% of software sold is games, and about 35% is business software.

ECONOMIST: MONITOR

ReDigi's software is designed to prevent sellers from reinstalling a sold song to their computer, and offers users the chance to check their libraries for illegal music.

BBC: US court to rule on ReDigi's MP3 digital music resales