180/360 VR backdrop renders

Has anyone done any renders to use as 180/360 degree 3d backdrops in a VR setting? Any tips/advice? Would like to do my own.
I've seen some advice on rendering the six sides as a cube map (x2 for stereo) and stiching them together (suitable app? free?)
Comments
bring this back to life for future reference - mCasual Jaques has some good tools/tutorials on this topic/technique on his googlesites pages and 'releases' and discusses them in the Technical Discussion forums here. Brilliant stuff.
--ms