A LiveDVD full of Computer-Aided-Engineering software, including free CAD-Programs, pre-/post processor and finite element solvers. Recommended for a first try.
For people who need a bit more complicated grids (of course you can always do it with blockMesh).
Very good overview of free and commercial mesh generators.
Netgen is an automatic 3d tetrahedral mesh generator.
It accepts input from STL, IGES and STEP file format from CAD.
Input format from CAD, IGES and STEP, supported.
Converting UNV file format to OpenFOAM search for "UNV" in the OpenFOAM Message Board 
Looking at your results in many colorful ways.
Paraview is the most common application to post-process OpenFOAM results.
Tecplot is a commercial post-processing tool notable for it's high quality images and simple to use macro recorder. See Tecplot for usage. Starting with version 2011, Tecplot has a native OpenFOAM data reader.
FieldView is a commercial application designed for visualizing CFD, CAE and multiphysics simulation data.
Latest versions provide the ability to post-process OpenFOAM cases directly, but OpenFOAM itself still provides legacy support for FieldView as described in the User Guide: 6.3 Post-processing with Fieldview.
3.6 Enthought scientific applications
Enthought has developed a variety of reusable components for building scientific applications. Get Traits, Chaco, and Mayavi, as well as all the other open source projects that Enthought has created for building scientific applications:
- Traits : Explicit type declarations; validation; initialization; delegation; notification; visualization. TraitsGUI: A UI layer that supports the visualization features of Traits. Implementations using wxWidgets and Qt are provided by the TraitsBackendWX and TraitsBackendQt projects.
- Mayavi: Interactive and scriptable 3-D visualization.
- Chaco: Interactive 2-D plotting for applications.
It may be interesting to see how we can link Traits and TraitsGUI with Contrib_PyFoam
4 GUIs for OpenFOAM
There is a growing number of Graphical User Interfaces (definition at Wikipedia) designed for operating OpenFOAM, without having to deal with OpenFOAM directly. For listing them the following dedicated page was created: GUI.