The worship environment - visuals
Some years ago, these were beyond the finances of most services, but prices have come down a long way along with their size and weight. Ideally, you'll want one that can take at least SVGA (computer) and Video-in (VCR). Newer ones also have DV (digital video) and other inputs.
Overhead Projectors are not as versatile at displaying fast changing artwork. They also have the distinct disadvantage of sending a lot of their light up vertically which can disturb the lighting ambience of the space. However, a way around this is to build a 'hood' of blackout fabric to shroud the projector between the face-plate and the reflecting mirror.
OHPs can be used to produce some imaginative effects: try putting a Pirex cooking tray filled with slightly warm water and some inks of different colors in the water. As the service proceeds, the shapes develop as the water warms. Dropping floating objects like leaves on the water can also give good effect.
35mm slide projectors used to be standard equipment for alternative worship services in the days before affordable video projectors. They still have their uses if you have the slide collections, or want to paper the walls with still images. Kodak carousel projectors are industry-standard, but for static images which don't change much, most cheap domestic projectors (often long-relegated to the attic) are quite suitable.
One snag to be overcome is how to access these projectors when you want to change a load of images all at once. One technique is to place as many projectors on a stack located in the centre of the space so that they can be controlled by one person. Another plan is to design 'extension leads' to the slide switches which run across the worship space to a central control point. At least one service has hooked up all the projectors to a computer-controlled relay box which is capable of interfacing with more than one design of projector through adapters and software control.
Although it's possible to project onto walls, a set of well-constructed calico sheet screens are a staple accessory. Run broad hems and casements top and bottom to thread support wires through with ease.
The method of supporting screens will depend on your venue. However, for churches and other buildings with pillars, one of the best solutions is to buy ratchet strapping of the kind used to hold surfboards in place on car roofracks, then thread D-rings through them and ratchet the whole thing tightly around the pillar. The D-rings then provide a very firm anchorage point without needing to drill holes in anything. The best support wire is high-breaking-strain stainless-steel sail wire, available from boat chandlers stores. A good chandler will make up hydraulically-compressed loops at each end. Then all you need is a barrel-strainer and some carbide hooks to make a wire support which can be tightened very rigidly so that the weight of the screen doesn't cause it to bow in the middle. Beware of over-tightening however: read the story of the death of Samson (Judges 16:29-30) about the dangers of exerting too much lateral force on building pillars!
Once you've got a set of screens, you can use them to subdivide your worship area - with enough screens, it's possible to have L or ever S-shaped worship spaces...
Many groups still use VHS players, especially if they have a library of loops from the days before DVD. The lucky ones have two hooked up to a video mixer with a monitor to cue up the other channel - very nice, quite expensive... Assuming you haven't got this, then unless you are going to produce your video for each service, it's good to have a second VHS hooked to a TV to cue up videos before playing them over the big screen.
If you can't afford a video projector, another option is to buy a set of second-hand (ex-rental) TVs and wire them together through a distribution amplifier or series of Y-splitters. Indeed, this effect can sometimes be more atmospheric than a plain projected image.