Repurpose those useless plastic cards

The thing is, I have a very high credit rating which in turn causes every credit card company to deluge me with an endless stream of pre-approved credits cards.
As somebody has already mentioned, I repurpose mine into guitar picks. I bought a guitar pick punch off of Amazon for about $20. Looks like a standard stapler.
Another good use is to use them as shims in construction, wood working, and even used them to even and stabilize work tables.