Spiderinabox provides an out-of-the-box solution for secure browsing on Mac systems. It includes a basic preconfigured installation of OpenBSD prepared as a VirtualBox image loaded with Firefox and a few scripts and programs to launch it and invoke Firefox over a secure connection. The visualization of Firefox is done on the OS X side using XQuartz, so you don't need to exit your working environment and switch between OS X and OpenBSD. Firefox runs encapsulated in OpenBSD and doesn't have access to OS X in any way.
