Entity-relationship modeling software

Solution 1:

Dia (Click to install)

Dia is roughly inspired by the commercial Windows program 'Visio,' though more geared towards informal diagrams for casual use. It can be used to draw many different kinds of diagrams. It currently has special objects to help draw entity relationship diagrams, UML diagrams, flowcharts, network diagrams, and many other diagrams. It is also possible to add support for new shapes by writing simple XML files, using a subset of SVG to draw the shape.

You can also use Pencil

The Pencil Project's unique mission is to build a free and opensource tool for making diagrams and GUI prototyping that everyone can use.

Solution 2:

Diagram Software

With Gliffy online diagram software, you can easily create professional-quality flowcharts, diagrams, floor plans, technical drawings, and more, with online diagram editor makes it easier than ever to create great looking drawings.

Gliffy can be used as...

• Flowchart software
• Network diagram software
• Floor plan software
• Org chart software
• SWOT analysis
• Wireframe software
• UML software
• Business Process Modeling
• Web Site Map Software
• Venn Diagram Template Software ...and more!

Solution 3:

Dia

ArgoUML

Solution 4:

I recommend you the Dia software which you can easily get from Ubuntu software center. It is easy drag and drop application for ER or any other UML or flow diagram and contains number of other shapes. For more information visit this link.