First of all I should point out that I'm quite new to Rails (and jQuery) and the interactions between it and JQuery, which may be the reason that some of you may consider this a rather basic hint.
However whilst working on membermeister.com I've recently had some trouble loading JSON data from our Rails backend. It seemed like a very trivial task at first, all we needed was a GET request that was answered by a format.json response from the Rails controller.
Simplified the request looked something like this:
url: "/invoices/" + invoiceid + "/pay",
However Rails was returning a '406 Not Acceptable' error, suggesting the request I was sending was not something it was instructed to handle.