Xmind - Xmind is a brainstorming and mind mapping application.
Diagramo - Diagramo is an online flowchart software - diagrams (create, edit and share)
MindMeister - Create, share and collaboratively work on mind maps with MindMeister, the leading online mind mapping software. Includes apps for iPhone, iPad and Android.
Modelio - Modelio is an open source modeling tool supporting natively UML, BPMN and model exchange with XMI.
FeatureMap - FeatureMap story mapping, simple and effective realtime collaboration and collective intelligence tool.
UML Designer - UML Designer provides a set of common diagrams to work with UML 2.5 models.