Folks,
Yet another variant on the computer/light mounting setups I've seen mentioned of late is my own. I got a cheap stem discarded from a kid's mountain bike, and a piece of handlebar from another cheap bike. Sawed the ends of the handlebar to the length I wanted, inserted a pair of handlebar end plugs, and there it is!
Some not-very-close pictures of this are on the group's site, here: ( http://ryanownersclub.com/scrapbook/tarmstrong/ ), with two sets of the 2000-ish Vista headlight sets mounted. I used the battery mount provided in one kit to hold the two NiMH battery sticks to the bike's frame, attached at two of the three bottle cage bolts along the top tube.
I've since removed one pair of headlights. I need to buy a replacement for the Zefal flasher, as it finally died a few months ago. I don't ride at night as much now, so I've not been in as big a hurry to get the new flasher. If you look closely, you can just see my computer on the cross-handlebar, just inboard of the bar-end to which are attached my right shifter and brake lever. Not easily seen here are my bottle cages, mounted to the seat stays--kind of like reaching to my back pocket for my water bottle as I ride. I used to have one of the AirZound horns, and kept the air bottle in a third cage, mounted inboard of my right bottle cage. The cage is still there, so I can carry three bottles of water easily. I've also trimmed the front fender braces to get the fender closer to the tire along its length.
The bike only has about ten thousand miles or so on it, and I expect it will serve me another several times that.
Tom, aka bikeolounger