Oh, this is the most facinating idea!!
A group of ladies at lifetimemoments have set up scrap accountability blogs where they are tracking their supply usage against their purchases.
I think if you are a list kind of person, this might be perfect for you too.
Here's Susan's blog that started it - if you look at the side, you'll see the other group participants.... Everyone has modified the rules a bit to suit their own needs, etc... but the basic idea remains the same...
Susan's ScrapAccountability blog
This would never work for me. But i find the idea facinating and genius!