The online file-sharing market had been simmering for a while, but it really bubbled up in 2012 when customers and companies recognized the red-hot potential of online collaboration tools. In May, EMC Corp. acquired cloud storage startup Syncplicity LLC and highlighted the purchase (the acquisition price was small enough so that EMC wasn't required to disclose it) at its annual EMC World conference in Las Vegas. EMC buying Syncplicity was considered a big step forward for EMC in the enterprise-level online file-sharing space, which is why it’s our fifth pick. EMC was apparently sold on Syncplicity's focus on security; the company's product is SAS 70/SSAE 16 compliant, and that means strict auditing security standards. In November, EMC announced plans to integrate Syncplicity with the SlideShark app. That means pairing Syncplicity's cloud-based file sync technology with the Brainshark app that allows users to share and view PowerPoint presentations on mobile devices like iPads.