This idea is something we would have loved to have thought of. A business card that turns into a wallet sized, battery-free speaker for your smartphone. (Something you should off course only do if you forgot your headphones)
Brilliant work from swedish ad agency Åkestam Holst for their client, the stockholm based hi-fi store, Pause Home Entertainment.
Last but not least, they carry our TMA- 1 headphones. What's not to like.