Diagramo - Diagramo is an online flowchart software - diagrams (create, edit and share)
asciiflow - Infinite ASCII diagrams, save to Google Drive, resize, freeform draw, and export straight to text/html.
Modelio - Modelio is an open source modeling tool supporting natively UML, BPMN and model exchange with XMI.
PabloDraw - PabloDraw is an Ansi/Ascii text and RIPscrip vector graphic art editor/viewer with multi-user capabilities.
UML Designer - UML Designer provides a set of common diagrams to work with UML 2.5 models.
JavE - JavE (Java Ascii Versatile Editor) is a free Ascii Editor.