Hey, just thought I'd solve your Velib mystery.
European debit/credit cards have a microchip on the right-side of them (as you're looking at the front of the card). The microchip is an alternative to the magnetic strip (and is in addition to it--their cards have the magnetic strip as well). Card readers at Velib stations can only read cards with microchips. Go stick your card into one and you'll notice that the card doesn't go all the way in. It would actually be impossible for the reader to read your American card because it doesn't have physical access to the entire magnetic strip. Be advised, the same applies in quite a few bars and restaurants--it's good to always keep a decent amount of cash on you in case you find yourself in an establishment like this. You really don't want to find yourself with no way to pay for your bill, and no way to even communicate with the business owner about coming back after you find an ATM or something.
By the way, I found your site because I'm in the process of making a new blog for kids ipad apps (primarily a reviews website), and I plan to monetize it. This led me (though another site or Google, I don't remember) to your How to Make Money article. Thanks for that. It's
Best Kid iPad Apps. If you ever have occasion to link to it, for example in an update to your Velib post
I'd sure appreciate it.
Have a great time in Paris. It's the best place in the world. Like one of the previous posters, I've always felt at home in Paris in a way that is both profound and difficult to articulate. And, condolences on your inability to use the Velib. It's an awesome system. You only need the debit card the one time to charge your metro card at the Velib station. After that you just wave your RFID equipped metro card at the pay tower, just like getting on the metro, and a bike is unlocked for you. It's all super quick and painless (well, except the part about having to open a European bank account).