@Michael - yeah we've been doing some direct contacting of people we find on the app store but it's been surprisingly time-consuming. LOTS of non-replies (I suspect the contact info most app devs provide isn't something they check all that often) and it's clear that many apps are really sort of in maintenance mode, living off of SEO more than new-feature development. We also don't want apps that are TOO huge for the beta-test time period... make sure we can walk before we run :)
Cocoacontrols is a great suggestion - we have a much bigger framework we eventually want to put out for people to try but smaller components initially is a good idea.
@Josh - reached out to you separately via email.