This little wonder is found on ThinkGeek. Pop in an SD card full of your favorite mp3s, pop the whole thing in your tape deck and enjoy. I may have to get one of these. I have a vehicle which still has a tape deck. It also doubles as a stand-alone mp3 player.

If you do a google search you can also find lots of references (such as this one) to the Abe BT 80c Bluetooth cassette tape adapter. That would see a lot more useful to me but, alas, I've scoured that company's website and can not find the product.

Via Jalopnik.