One item I have found incredibly useful in the past 7 years is an LCD video projector with a station containing VCR, Computer, Videodisc (DVD), and Video camera.
the large display projected on a large screen has been great, even with the somewhat fuzzy interface between our Mac and the video out. The projector does cost a bit, but the relative image size is well worth it. Other rooms have 27" monitors attached to the wall by a brace. My image is closer to 97"! Some stills allow for one to see the individual pixels, but these seem to not be noticed when the images "move".
I would have imagined the prices to be under $1000 now since we paid about $2000 years ago. This is one piece of technology that just doesn't want to go down in price. But once again, I believe it is worth the price, particularly if you are in the design phase.
With a cheap camera handy (even one of those digital one's for the computer) one can quickly do an experiment based on a student's suggestions. For example I tape a little flashlight on a plunger's center of mass and then throw the thing across the dark room. The students will say that they saw the light travel in a parabola, but when you tape it and show it instantly, projected on a white board, you can actually follow the trajectory and show that indeed the motion of the COM is parabolic. I'm sure you, or others can think of thousands of other uses for quick video use and the extra size is worth it.