As it turns out, there are a few major shoe companies that have wear testing programs. The two that come up most immediately with an internet search are Brooks and New Balance - and I immediately applied for them. Pearl Izumi also has a program, but they aren't accepting applications for it right now.
That was a couple weeks ago, and I just got an email from New Balance saying they were sorry, but they don't wear test shoes in my size. (But with a 10% coupon for their online store attached, which was a classy touch.) I guess test shoes don't come in 13s. Oh well. Haven't heard back from Brooks yet, but I'm assuming it'll be a similar story - unless Brooks is going to try to cater to the large-footed runner out there.
Anyway - has anyone else had any experience with these programs? Are they a good deal, an interesting way to try out a bunch of different types of shoes, or what?