For instance I go to planscop.io and I am told "Project Management for Contractors - Planscope is a simple tool that helps you build better client projects and close more deals.". I know it is for contractors for managing projects.
NewRelic.com - "A DEVELOPER’S BEST FRIEND - See how we help 25,000+ customers monitor their apps." I know it is for Developers and it monitors my apps.
Risks.io - "Track Your Project's Risks, Assumptions, Issues and Dependencies Online"
Basically I think work.io does is "Work.io connects employers and knowledge-workers together for highly-skilled one of projects."