Well I've been using ACID for about 18 months, (since ACID 1.0 build 41), and IT"S DA BOMB !!!!!!!! 
Check out my review in  http://www.sharbor.com/products/SFOI0250010.html 
after reading it, you will be amazed at this apps versitility, and performance. 
Now, the tricks and tips are various. 
If you have any questions about a specific trick, or something you want to attempt in ACID, email me at  DJ_Devious_D@Hotmail.com 
I use a mirad of sounds. Things I create in other apps, (like FruityLoops, HiPHop EJay, Cool Edit Pro), then I import them into ACID 2.0.
You can even use ACID like a MultiTrack editor....
I'll create a track from FruityLoops, then I'll ACIDIZE it, then import it as a WAV file into ACID, then overlay or mix in ACID pre-recorded loops, or original loops of my own.
I can go on for minutes about this, but I digress.....
----Original Message Follows---- 
From: "Peter Shindler" 
Reply-To: Loopers-Delight@annihilist.com 
To: 
Subject: Acid 
Date: Thu, 4 May 2000 23:46:39 -0400 
I'm curious to know how many loopers are using Acid, and I'm also hoping to 
get some ideas. I've had it for about 6 months and I think I'm just 
starting to see its potential. 
What do you use it for? Do you mostly use the sounds included with the 
program, or bits from other recordings, or samples of your own playing, or 
what? Any tricks or tips to share? 
Peter