Just before the holidays I learned about the Joann Fabrics VIP card, I heard it in their stores via overhead commercial, then it was in their sales flier.
This is a program where you get an additional 10% off every purchase when you shop in their stores. The sign up was on the website, and was quite easy you need to be a reseller or a non profit organization to qualify. The sign up can be found here, once you sign up they say it takes 3-4 weeks to get your card, I got mine in less then 2 and this was at the holidays.
Once you receive your card you will need to take it and have it validated, to have it validated you will need your tax ID, take a copy as they did ask to keep it. You 'should' only have to validated at one store, but then should be able to shop other locations.
The VIP card is valid for one year, though mine expires 8/31/11, which is not quite a year, I have read you can re-verify/apply over the phone. I would also guess you will need to have it verified again at store level.
I have found this does not make your purchases tax exempt, you will need to fill out additional forms for this qualification. You do need to do this at each location, and they still verify it each time except the one store where they kind of know me. For the tax exempt status you will need to provide a copy of your tax certificate, I always keep a spare copy on me for this reason.
Overall this is a very worthwhile step to take, it is relatively easy and saving 10% on everything sale and non sale items adds up over the year. I will also add, I know retail settings can be different, being overly prepared is good, this was my experience here in the Metro Detroit area.