Ideament!

yEd is a powerful diagram editor that can be used to quickly create diagrams manually or import external data for analysis and auto-magically arrange even large data sets by just pressing a button. You can use yEd to quickly create flow charts, BPMN and UML diagrams, organization charts, mind maps, and many other kinds of diagrams, graphs, and networks. Choose from a wide range of highly sophisticated layout algorithms to automatically arrange diagrams in no time. An intuitive and visually appealing user interface makes creating diagrams fun. Once a diagram has been created, it’s easy to save, print, or export it to popular formats like PDF, SWF, EMF, SVG, JPEG, GIF, PNG, or HTML image maps. »

Draw lets you produce anything from a quick sketch to a complex plan, and gives you the means to communicate with graphics and diagrams. With a maximum page size of 300cm by 300cm, Draw is a an excellent package for producing technical drawings, general posters, and much else.

Microsoft Office Visio makes it easy for IT and business professionals to visualize, explore, and communicate complex information. Go from complicated text and tables that are hard to understand to Visio diagrams that communicate information at a glance. Instead of static pictures, create data-connected Visio diagrams that display data, are easy to refresh, and dramatically increase your productivity.

Graphviz is open source graph visualization software. It has several main graph layout programs. It also has web and interactive graphical interfaces, and auxiliary tools, libraries, and language bindings.

Mindomo is the easiest online software for creating mind maps, concept maps, outlines and various other types of diagrams. The following features make it the perfect choice both for business and education:* real-time collaboration* you can work on maps even if your internet connection is down, and your changes will be automatically synchronized when the connection is restored* playback mode that shows you how a map was built* maps can be turned into presentations or real-time editable outlines* Google Apps and various LTI integrations (Canvas, Moodle, Blackboard, Desire2Learn, itslearning)* great variety of exports (PDF, RTF, PPT, TXT, OPML, MPX, HTML, ZIP, PNG, XLS, MOM, MM, MMAP)* Google Drive, Dropbox, FTP and ZIP backups »

OmniGraffle can help you make eye-popping graphic documents—quickly—by providing powerful styling tools, keeping lines connected to shapes even when they’re moved, and magically organizing diagrams with just one click. Create flow charts, diagrams, UI and UX interactions, and more. Whether you need a quick sketch or an epic technical figure, OmniGraffle and OmniGraffle Pro keep it gorgeously understandable.

Simple vector graphics editor for creating flowcharts, UML class diagrams, illustrations and slide shows.

PathVisio is a free open-source pathway analysis and drawing software that allows drawing, editing and analysing biological pathways. It provides a basic set of features for pathway drawing, analysis and visualization. Additional features as plugins.

Generate diagrams from text faster than ever and facilitate stakeholders involvement via animation and online collaboration.

Theory Maker is a free web app by Steve Powell for making any kind of causal diagram, i.e. a diagram which uses arrows to say what contributes to what. You make the diagrams just by typing the names of the elements (called variables) in a structured way into a (resizeable) window, and you get a live diagram as output which reflects what you type.