edit: changed the name of the thread from Old School 3D Movies Outdoors! to Anaglyph 3D Movies Outdoors!
found this bit of software recently.DVDFab 2D to 3D Converter
input: 2D DVD/Blu-ray disc, 2D DVD/Blu-ray folder, 2D ISO image file, 2D video
output: 3D video: AVI, MP4, MKV, FLV, M2TS, TS
Users can get the output as one file in side-by-side or top/bottom format, or as 2 separate files (one for right eye, one for left eye), or as anaglyph video with 14 modes available such as Red/cyan, Green/magenta, Amber/blue, Red/green, and Red/blue (monochrome / half color / full color / high quality Dubois).
its a little expensive. MSRP of $60. there is a 20% off deal right now though so it comes out to $48. i'll keep an eye out if it goes on sale somewhere, but that would be cool in case because i would be able to have all my regular movies and have the anaglyph version "for whenever i feel like it"