There is a handy new link on each of the "Beer Me!" brewery and index pages. Clicking on [Nearby Breweries] will bring up a map of the 20 breweries closest to the one you selected.
The new [Nearby Breweries] link is circled in red.
It's not perfect, but it's better than what I had before, and I'll be smoothing out the features in the coming days.
Thanks to Boris Georgiev for the idea and to Jonathan Surratt of beermapping.com for the technical tip that makes it work!