http://vsoc.berkeley.edu/vsoc/
It is currently available only for the Macintosh platform,
but a Windows version will also be released in the near
future. This is still an early beta release.
It is probably not suitable for serious science, but we
would be delighted to be proven wrong.
This is a team project by Matthew Peterson, Jesse Paquette
(undergraduate student on-leave from Kalamazoo College)
and myself.
Enjoy,
Izumi Ohzawa
UC Berkeley, School of Optometry/Vision Science