Is there a plugin for advanced digital downloads and team management?

Hi,

I’m wondering if there is a plugin or other solution (multiple compatible plugins?) for building a highly customized site that encompasses digital downloads and a platform for managing contractors within the site. For example, a site that deals with contractors, clients, and a digital product, like iWriter or Elance (extreme examples – but basically a scaled-down version of that). Or do I need to hire a developer for that?

Any advice will be much appreciated.