FFS, I don't know why people keep banging on about dub sirens. There are about 270 thousand dub siren circuits out there if you look on Google. They all amount to much the same thing - a pair of 555-type oscillators, one slow one and one fast one. The fast one makes a tone and the slow one makes it go "woowoowoowoowoo". It's not exactly rocket science.
It's the attitude to it that s-cat has that gets me, this whole "oh I know how to do it and no-one else does and I make the dub sirens and mine are the best" - get stuffed, matey. Oh wow, we're all so terribly impressed that you can build a circuit that is pretty much part-for-part identical to the one in my CSYS Physics textbook from the dim distant pasts of 1990, and reproduced all over the Internet. Get real.
If anyone wants to build a dub siren and can't figure it out, feel free to ask me for help. If you're totally stuck, come round to my house and bring the siren components and some real ale. The circuit-bending community is about sharing. Not "zomg yuo might copy my l33t designs" secrecy, and not "show me everything so I can slavishly copy it", but properly sharing.
Time Mr S-Cat learnt this...
[originally posted while seriously annoyed at someone else for exactly this reason, edited slightly for language]