Credit cards, bank cards, store rewards cards, and hotel room cards can be shredded or tossed. But as long as they aren't laminated, they can be reused. I saw the following tips on www.creditcards.com. They can be useful as cable organizers. If they feel flimsy, then glue a few of them together to create more support for heavier cables.
The next one I really liked was to trace a guitar pick with a sharpie on a plastic card then cut out the design with scissors.
For more ideas on reusing cards, you can go to http://www.creditcards.com/credit-card-news/8-crafty-ways-recycle-reuse-credit-cards-1273.php