Modelio - Modelio is an open source modeling tool supporting natively UML, BPMN and model exchange with XMI.
AirHelp - Get paid when you're delayed!
Diagramo - Diagramo is an online flowchart software - diagrams (create, edit and share)
Service - Customer service issues solved for you, on demand, for free.
UML Designer - UML Designer provides a set of common diagrams to work with UML 2.5 models.
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.