First of all, this Instructable isn't a step-by-step from-the-ground-up creation or even a hack. Its more of a ... re-purposing, I guess. Ok, ok. Lets just say it's a cool use of technology.
For several years Best Buy sold very unique Holiday gift cards: they doubled as some sort of electronic gizmo! One year the "gift card" was a simple audio speaker, complete with a short cable and 3.5mm jack. Another year the gift card included a string of USB-powered colored LED lights. Since you bought this double-duty thing as a gift card, you could put any amount on the card and not pay extra for the gizmo! Sooo for $1 you could get the speaker or the string of LEDs!
For Christmas 2007, Best Buy offered a gift card that doubled as programmable scrolling LED mini-sign. It was very similar in function as the LED name badges you can find on ebay and elsewhere.
So I bought a bunch of these, putting $1 on the gift card. I programmed them with my family's names and used them as gift tags!
This video shows the gift cards in full use at my in-laws for our big family Christmas 2007 celebration.