Is there a plug-and-play card swiper for iPad to get data from the card? We are in the process of assembling iPad kiosks.

We are not writing an iOS app, iPad will just have a bookmark to a web application that will be hosted on our server. As far as the user is concerned, he won’t be able to really tell if it is an app or a website.

We need to be able to read membership numbers from a membership card, which is just a plastic card with magnetic stripe on it. I am told that to be able to use any swiper I need to write some custom code, but we are not writing any code, we are just pointing to the website.

Is there a plug and play swiper? Maybe I can write some simple iPad app which will run on the background and will be able to accept input from the swiper and pass it to Safari, so webapp can get it? Hope it makes sense.
No, there is no way you can do that. Apps can’t pass input to each other. Though there is a method which can be modified to do that, it definitely doesn’t suit you. You will have to write a custom app and use the Square card reader or alternatives.