Official OpenFOAM: www.openfoam.org www.openfoam.com
OpenFOAM-dev: http://sourceforge.net/projects/openfoam-extend/, this is a user-driven collaborative project.
Please note that the OpenFOAM-extend project is not affiliated with OpenCFD; OpenFOAM-extend is a community-driven project.[1]
OpenFOAM-extend Project: http://www.extend-project.de/
OpenFOAM Discussion: http://www.cfd-online.com/Forums/openfoam/
OpenFOAM wiki: http://openfoamwiki.net/
H. Jasak Homepage: http://www.h.jasak.dial.pipex.com/
OpenFOAM workshop saved by FSB: http://powerlab.fsb.hr/ped/kturbo/OpenFOAM/
OpenFOAM Workshop: http://www.openfoamworkshop.org/
FoamCFD: http://www.foamcfd.org/
Chinese OpenFOAM Discussion: http://www.cfluid.com/bbs/forumdisplay.php?fid=86
SU Junwei Blog: http://blog.sina.com.cn/openfoamresearch
note: some of the websites cannot be visited in China, please use proxy if you are in China.
References
[1] Differences between 1.5.x and 1.5-dev. http://www.cfd-online.com/Forums/openfoam-code-other/64825-differences-between-1-5-x-1-5-dev.html#post218416