Search members by geographic proximity?

I’ve found a plugin (not by wpmudev) that more or less does what I want, but I’m wondering if there’s anything here that allows users to put, for example, a zip code in a profile extended field and make it searchable (and sortable) by proximity…?

Any other solution would be fine – I’m not picky. But I’m working on a site that is essentially a matchmaking site, and it would be great if people could see which members were within a reasonable distance.