You know, I wondered about this myself, so I did some research on what kind of craft projects people are doing with spent gift cards. There are some pretty neat ideas, and I came up with a few of my own, too.
My favorite idea is to make guitar picks out of them. You can buy a pick maker (this one seems to have the best reviews, though I haven't tried it myself, as much as I'd like to:
http://www.amazon.com/Guitar-Palooza...pr_product_top). As someone with a kid who goes to Rock Band Camp throughout the school year, I would love to take them a stack of guitar picks. You can also cut them out yourself, tracing around a storebought pick with a Sharpie to get the shape right, but I find that mine always turn out lopsided with this method. The nice variety of Chase gift cards available would make quite a nice set of different picks to give away, I think.
I also think it would be neat to turn one into a luggage tag. With a hole punch to make a hole (or a grommet puncher if you have one) you'd have a nice sturdy base. Put a white sticker with your name and contact info on the back, cover it with clear tape and you have a pretty and unique luggage tag that will stand out, and has your name on both sides. If you're worried about the numbers showing even though the card is drained, you could color over them with an oil-based paint Sharpie (they still show through regular Sharpies) or cover them with a strip of colored duct tape.
I also cut out batarang shapes from them as accessories to a costume I wore to Comic-Con last weekend, used silver or black oil-based paint Sharpies to cover them, and handed them out to people who identified the character I was dressed as. That was a lot of fun.
People have made keychains, jewelry, and used them as covers for little journals filled with re-used paper (such as the blank parts of the letters that Chase sends with the gift cards).
Oh, I also cut out the "Visa" part in the corner of each card and turned them into a miniature credit cards for my daughter's dolls. She loves them. I dug up some canceled credit cards to give her Mastercards and Amexes, too.
I hope others will post their ideas.