Topic: Revenge
If the noisy neighbours are under 25 and you're older, you might be able to use your hi-fi to get them back.
This is probably reckless and inadvisable, but I just wanted to put this out because I don't often have good ideas. Feel free to shoot me down in flames.
Try this website to get an idea of the frequencies of sound you can't hear (but they probably can): http://audiocheck.net/audiotests_frequencycheckhigh.php
Then it's just a matter of burning a CD with a few seconds of the lowest high frequency you can't hear (if you see what I mean), put it on repeat, and crank the volume to the max.
Make sure none of your "good" neighbours will be affected though...
If there's any interest, I can give better instructions.