I recently had to make a "register with Facebook" feature for one of my customers (for web, not mobile). To do so I needed to grab the user's email, but official Facebook plugin does not have this feature. So I ended up rebuilding the official plugin and I thought some of you may find it useful.
It's the exactly same plugin as the (current) official one with just one expression more which allows you to fetch the user's email address.
Please note that this plugin does not overwrite the official one. After installing this plugin you will have two Facebook plugins in your C2. One will be called Facebook (which is the official one) and next to it you'll find Facebook2 (which is the one I'm sharing here).
DOWNLOAD: Facebook2 plugin
Ashley could you consider adding this expression to the official plugin? It's actually just to copy and paste the code from this one as it is built on the latest official one.
Here's a tiny snippet of how to fetch the email.