I like to keep it simple. Okay that’s not true. I always like to be prepared for anything. That’s why I carry my own pocketknife with me. Always. My wallet is not just my wallet, it is more like a purse with a tweezer, band-aids, a nail polisher, tissues and many many more stuff.
I also have a usb-stick hanging on my home-key. And I can recommend it, it always comes in handy. Prada designed a pretty cute one. Only a usb can be tacky enough to be cool again.