A custom floor-standing frame could also be made from 1" angle iron by anyone with a small welding set. The design would suit your own equipment and operating styles, and have raised shelves at the back to hold equipment on plywood or blockboard shelves. The legs might also have office-style shelves, or drawers taken from old kitchen units.
The Chair.
After the bench you'll need something to sit on. This should be very comfortable, as a contester will spend many hours in the same position, but an old armchair is perhaps not the best choice, in case you fall asleep whilst waiting for 20m to open. The chair should be firm with support for the lumbar region. Some operators like a chair with arms whilst others find they get tangled in the headphone cables and stop the chair being brought close enough to the operating position. My own preference is for a typist's chair, which are specially designed for long term support and comfort. Mine came out of a Skip and was recovered with some old material and a staple gun, but you can usually find office-surplus stores in a city where such a chair can be picked up quite reasonably. For more information on all aspects of the operating-chair, read the interesting article at the Yankee Clipper Contest website.
Lighting.
Lighting is something else to consider. The existing room light will usually be behind you, causing your body to cast a shadow on the operating desk. Some small spotlights can be installed above the operating position, and should be angled to illuminate the desk without relecting on the computer screen or other equipment which might then be difficult to read. An anglepoise light is the choice of many operators, and can be added without a rewire of the room. Don't make the operating position too cosy however; a brightly lit room is better to stop you falling asleep in the middle of the contest.
Ergonomic guidelines for station design.
The following comes from an email sent by Dave, WD5N, to the CQ Contest reflector:

Since the subject was raised and there appears to be some interest, thought I would pass along some ergonomic guidelines that Texas Instruments (my day job) uses for workstation design. As it is intended for people who sit in front of a computer all day, it seems like it should apply pretty well to contesters!

Step 1: Adjusting your chair:

1. Height: thighs should be parallel with floor and heels resting comfortably on floor. Knees 90-110 degree angle.
2. Adjust the chair back (if possible) so the contour fits the contour of your back. (If not possible, try the lumbar support pillow).
3. Arm rests should not be too high (they shouldn't cause you to "hunch" your shoulders).

Step 2. Finding the right workstation height:

1. With your arms in a comfortable typing position (relaxed shoulders, arms hanging loosely at sides, elbows at 90 degree angle, wrists straight or neutral position), your hands should now be on the keyboard. (see note on footrests later)
2. Remember, as someone else noted, sliding keyboard trays are available which attach to the underside of your desktop; very handy if your desk is too high and/or not enough room on a short desktop and it slides out of way when needed.

Step 3. Correct monitor height:

1. Screen should be 16" to 22" from your eyes.
2. Adjust so the top of the screen is at eye level. Bifocal users may need to lower it to a comfortable level.
3. Tilt or use a glare filter to reduce glare from overhead lighting.
4. Adjust brightness & contrast controls to ease eyestrain.
5. Green-yellow colors are easiest on the eye.
6. Clean your screen and glare filter regularly for dust build-up.
7. Take down decorations, notes, and other distractions around your screen; Your eye muscles are straining to focus on these as well. (hmm, what about schedule and band opening reminders and inspirational signs like "Think Loud!)

Other areas:

1. Wrist rests: help support the wrist but shouldn't immobilize them (don't become too dependent and lazy).
2. Footrests: help support the feet and provide better blood flow through the legs. Thighs should be parallel to the floor when the feet are supported. Anything will work: use an old telephone book, two 3-ring binders taped together, etc. NOTE: thighs should be parallel to floor whether using a footrest or not. This is basically to adapt for other things you can't adjust. For instance, you may not be able adjust your workstation height and chair height to match the previously listed parameters. If your desk is a set height, and you have to raise your chair so your arms are at the right angle for the keyboard, then you may need to add the footrest to get your thighs parallel again. Or maybe you just have short legs!
3. Area layout: this should all be obvious, with things you need to look at or reach for closer than things you don't need access to as often.
4. "Document Holder" - we don't use these, but the ideas should be the same for other thing(s) besides the screen that you look at often (like a radio): First find your "dominant" eye (yeah, that's the first I heard of it, too) by holding up your hands together at arms length and make a "peep-hole" with your thumbs and forefingers held together (this is easier to do than to de- scribe - or just take a piece of paper and cut a hole 1 or 2 inches in diameter and hold it up), now look through the hole at a distant object with both your eyes open. Without moving your hands, close one eye, then the other. Your dominant eye is the one with which you continue to see the object (with the other, you see something else to the right or left of the object). Your dominant eye is the one you focus with first when you look at something. The document holder (or rig) should then be on the same side of the screen as your dominant eye, and it should be the same distance from your eyes as the screen so you don't have to refocus to a different distance. Now, this isn't always the best setup for radios, if you have to keep reaching up to tune it or adjust stuff. Might work if you have one of those cool remote tuning controls, or if you can remotely tune from the keyboard (another hint for N6TR and others). Lots of folks seem to like the rig directly below the monitor, or slightly to one side so they can rest the elbow on the table while tuning. Sometimes the keyboard gets in the way of this, but smaller keyboards are available (as are new keyboards with the keys angled to fit hands better).

That's about it. Others are sure to have little hints, such as standing up every so often and stretching and moving around. You really should do this at least every 30 minutes. The more often you do it the better you will feel (and more alert). No need to stop operating as you do it. Yeah, I know Trey [N6TR] likes to slouch in his chair with the keyboard in his lap as he breaks records, and some people like to put their feet up on the table. (and WB5VZL likes to sleep on the floor under the operating desks during multi's - go figure). Whatever feels good. But remember that while slouching feels really good at first, it usually isn't good to stay that way too long (unless of course your chair and station are designed to operate that way - who needs Herman Miller chairs, get a Lazy-boy!)

Hope this info comes in handy for some of y'all. Look over past issues of the NCJ also, good ideas in there.