Outdoor home theater is one of the newest trends in consumer electronics. The idea of the swim-up or backyard home theater is tempting to all Americans as they look to technologically upgrade their homes or entertain their families during the summer months.
With many projectors costing less than $1,000 and being very small and light, all you need is a screen, an extension cord and perhaps a DVD or Blu-ray player to have outdoor movies. Screens for these systems can range from a white painted chunk of drywall or a sheet (if you are really low budget) to slightly more expensive options, such as screen paint that makes for a pretty good movie-watching surface. Better solutions include fabric screens that can snap into place or easily be hung and manually rolled down. Those are normally best ordered with very heavy weights at the bottom so that they don't blow around in the wind. The coolest outdoor screen solution is Stewart Filmscreen's Starglas (shown), which is a specific formulation of reflective glass that can be installed outdoors and only needs a little Windex to clean up before a Saturday of college football in the backyard.
Elite Screens also makes several lines of portable screens that would work outdoors.
If you're concerned about the brightness of the projector outside, check out this article on screen gain.