As long as there are neighbours, there are neighbours with noisy dogs. While my opinions on people who make no effort to control their pets' noise are probably best not discussed here, there is a humane way to take this matter into your own hands...
I had been woken by incessant barking at 3am one too many times, did some research and came across several products designed to help manage noisy dogs. While some of them are designed for your own pets - like collars that emit high frequency sound or sprays of water triggered by barking (neighbours take note!); Others are designed to help control other dogs in the immediate neighbourhood. There is a siren that is camouflaged as a bird house that emits high frequency noise, triggered by barking that you can mount alongside your noisy neighbours' garden. I was not about to spend ZAR1000 (~$100) on a gimmick that I wasn't sure was going to solve the problem though.
Based on these existing products I came up with a cheap, make shift solution, using an old Nokia cell phone...
All you need to do is set a high pitched frequency as the tone for incoming messages and set the volume to maximum. The idea is that now when your neighbours' dogs get into a barking frenzy, you simply send an SMS message to your old Nokia cellphone (a 'please call me' works great) and it triggers the high pitched ring tone, discouraging your neighbours' dogs from barking. It's simple but it actually works.
I use a 2 second long, 8000 hz ring tone on a Nokia 5000D and this seems to be quite effective in training my neighbours' border collies to stop barking incessantly (different frequencies may work better for other breeds of dog?). I popped the phone into a tupperware to keep it protected from sun and rain and I need to charge it about once a week but it works great!
I don't trigger the tone every time I hear my neighbours' dogs bark - I save it for those times when they enter a torturous trance of looped barking. Sometimes I do need to trigger the tone two or three times, but it always works to break the barking cycle and certainly beats getting out of bed at 3am. It has also helped to make the barking episodes far less frequent which I think suggests an element of learning on the dogs' side.
Some peace and quiet at last :)