World's smallest, simplest and cheapest flashgun!
Remember the old fashioned Magicube flashes that sat on top of a Kodak 110 mini instamatic camera? They were surprisingly powerful, equal to a Sunpak GT32.
Inside a Magicube is a tube full of oxygen which when tapped by the internal spring would shoot up and mix with the zirconium foil in the glass orb and instantly give off a really bright light. 180 degree spread of light lasting about 1/30th of a second, just right for illuminating a waterfall but without freezing the moving water, brilliant! With a guide number of 80 in feet at 50ASA, because that's what 200 comes down to when underground, this was one of the most powerful guns available without going overboard with the costs. Remember, this was the late seventies and almost everyone was on the breadline.
The little alloy plate and galvanised sheet tin holder / trigger cost less than fifty pence and took me only an hour each to make. All three of us in the AVRG cave photography group had one or two and is what most of the caving pushbike was lit with.
This was back in 1978-82 when over a four year period I went caving 400 times and took one roll of film each trip. I can hardly believe that I ended up with 15,000 slides on Ektachrome 200. Being a self develope film the costs were kept to a minimum at £19 per hundred foot roll, enough for twenty times thirtysix exposures. Add on the tiny expense of a developing kit, plus hours of fun chattering and twiddling the films in their tanks, sometime three at a time with the chemicals being poured from one tank to another. We talked photo and took photos and there was little time for anything else, but then, what other hobby is so versatile in the areas into which you can lose yourselves for hours on end?
Obviously there was great excitement as super picture like these were revealed after fifty minutes of twiddling. God, it's fantastic that nowadays we can download five times that number and see the results straight away and print them off before an old slide film was anywhere near dry.
The hieght of our cave photography was taking a pushbike down Swildon's Hole on the Mendips. This was to be for an audio visual to show at the Bristol University caving conference. Once word got out the main lecture theatre was bursting at the seams with almost double the fire safety recommended numbers crammed into every corner, even sat on the stairs because they'd heard of the content. What!? Took a pushbike down through Swildon's!!! Definitely our happiest hour!
I'll be trying my best to put this AV on the net and let you have the link as soon as I can.

Fifty foot flashgun trigger for less than twenty quid including postage from Hong Kong. Absolutely the best gadget for using an off camera flash ever!!! I've just sent off for a second one so I can fire two flashes without having to resort to a mini slave unit, which don't always work 100% when working near sunlight.
Ebay has plenty of these triggers listed, just make sure it is a radio trigger and not infra red operation as these can cause problems outdoors. Go to :- John Camera Shop
You get two AAA batteries with each trigger but they don't last long (about 500 operations before they're flat - you'll notice this when the working distance starts dropping dramatically) Duracells should last for several thousand flashes. There's a fairly rare battery in the transmitter but Googling in the details finds a replacement without a problem.
After using this for a few months and finding that the working limit really is about fifty metres I took a soldering iron to the reciever, added a mono mini jack socket, made up a 5 metres lead and can now use the transmitter to fire my camera from over a hundred feet (useful for birds / wild animals / motorsports etc).
The first press focuses the camera and the second press fires the shutter. Am having great fun with this setup as you can see by my self portraits.
Inside the top of the reciever are two wires connected to the hotshoe. I joined both of these to either side of the mini jack socket and can now use still use it for either flash or camera, obviously not both at the same time or your flash will go off before the shutter is fully open. I've not set this up alongside a speed camera, yet, but you could have some fun and maybe save a life by giving it a whirl.
You'll have noticed that the hotshoe only has two contacts so it works my Vivitar 285HV no problem. Those of you with a Cannon 580 / 430 or a Nikon type flash would have better results by slipping in a piece of plastic from a sandwich or cake casing available from your supermarket, or use a section of milk carton. Cut out a tiny square with a hole in the centre for the middle contact of your ETTL / TTL flash, into the hotshoe before fitting in the gun.
I'm guessing that you are by now beginning to get the hang of using your flash and camera both in manual mode as us strobists do, if not I will be posting up how you can learn this fascinating technique soon as time permits.