A fine place to download a compiled package for the mac is this page of the ETH of Zurich. The OpenFoam package comes with some limited documentation. Many people have put extra info on the web:
macopenfoam for a prebuilt package for mac
openFoam 2.0 for MAC 0S 10.7
OpenFoam 2.1 for mac OS 10.6
code saturne on mac
J.H. Ferziger & M. Peric "Computational Methods for Fluid Dynamics" (Springer)
To theoretical for me.
Goro Tamai, "The Leading Egde", 1999 Bentley Publishers
Very interesting and readable !