These are sounds recorded at Halloween '98 by Stephen.

Various Screams

Screams 2
Screams 3
Screams 4

How to scream - Michael and Adam telling the best way to scream.

For these, you just had to have been there/know Justin.

It's the end of the world as we know it! (Justin and several others singing)
Freddy will get you in your dreams! (Justin)
Where's my head?!? (Justin)
What a wonderful world! (Justin)