LucidChart - LucidChart is the missing link in online productivity suites. LucidChart allows users to create, collaborate on, and publish attractive flowcharts and other diagrams from a web browser.
Inkscape - Inkscape is a free, open source professional vector graphics editor for Windows, Mac OS X and Linux.
UModel - UModel is a web-based tool that enables developers to use UML diagrams to express their software requirements.
LaTeXDraw - LaTeXDraw is a graphical drawing editor for LaTeX.
Topcoder - The Topcoder home page has received a slick new makeover that lets new customers quckly login, discover the power of our community, and launch challenges.
Ipe - Ipe is a drawing editor for creating figures in PDF or (encapsulated) Postscript format.