a few acidy suggestions. not all obvious sirens but very ravey synths that give the same effect

hazchem 3 - schlagg "elephant hunt" (the most f'ked up rave siren ive heard)
routemaster 6 - both sides, although the b-side (shizophonic) is truely messy!
the weathermen - domination (boscaland) big **** off hoover siren! ZEEEEEOOOOOWWWWWWwwwww.........


and of course "acid airaid" on choci's chewns absolute classic!