Splitting a light beam into opposite circular polarizations?

[jimgraber]

Is it possible to split a single light beam into two beams of opposite circular polarization?
A properly oriented calcite crystal will separate a unpolarized beam into two beams, one vertically polarized and one horizontally polarized. Other polarizers pass just one polarization and absorb the perpendicular one.
Is there a device that splits an unpolarized light beam into a right circulaly polarized one and a left circularly polarized one, instead of just absorbing one or the other?
(If so, please tell me where I can buy one.)
If not, is this theoretically impossible?

 

[Simon Bridge]

You'd make one with a normal beam splitter and two quarter-wave plates.