I use the nVidia 3D Vision system. So, for movies/vids I play it in the 3D Vision Stereoscopic player which supports over/under, side by side, or interlaced formats. It will open DVDs too but so far there is no support for Blu-Ray. I can also run a plug-in that will convert 2D videos and DVDs to 3D, but honestly the conversion stuff sucks and probably always be nothing more than guesswork.
My projector is officially supported for the 3D Vision system so it's easy to set up (I did a review on the 3D Display section of the VS PJD6210). There is a USB dongle that sits in front near my pull down screen that syncs with the active shutter glasses. Games are ultra immersive, but I have some 3D HD trailers too like Bolt that are quite impressive and in some ways better than what you see at a theater (mostly likely attributed to the active shutter tech vs polarized glasses).