SharePoint 2010: Create Site Column based on External Data

While the process to create a site column based on external data is pretty straightforward, I wanted to document it here for myself; I keep forgetting that this can't be done using SharePoint Designer. Here's how to do it using your a browser:

Create your External Content Type and associated lists -> Site Actions -> Site Settings -> Site Columns -> Create -> Name your column, click Lookup, wait for the webpage to refresh -> Get Information From (select your External List) -> OK -> Party!