Is it possible to generate a QR Code inside of the browser (across the popular browsers)? Ideally using JS and CSS, if HTML5 is required that is a possibility as well.
If so, does anyone know of a good script to do so?
Actually yes, using Canvas you can draw QR code, and it can be saved as image. Look here - looks like pure HTML5 implementation, you can investigate its scripts qrcode.js and qrcanvas.js, as well as you can use it under the MIT license.
As it is written on that page, it won't work on IE, but you can use emulator there.
There is also another article, how to generate QR code using jQuery plugin, but they just use online generators (Kaywa & University of Bath services). This way is simpler and should work on all browsers ;)