Mobile apps are proliferating so quickly that getting yours discovered is a big challenge. Leading New York startup incubator Betaworks (Twitter, Tweetdeck, Bitly, Tumblr), in collaboration with technology shop Prehype and NYC tech community organizer Nate Westheimer, have launched a new app promotion service that brings a familiar formula to a new mobile app context. It’s called Allify.

The idea is simple: run ads for other iPhone apps on your app or web page and get credits to apply toward promotion of your app in other peoples’ ad space.

The service is in private beta right now, so participation is by invite only. Hopefully the service will open up to app developers in general soon. If it remains a hip New York insider’s cartel of self-promotion indefinitely, that sounds obnoxious. Hopefully Android will get some love, too.

Cost and business model haven’t yet been disclosed, but it seems like a good solid strategy. Great apps sometimes promote themselves, but for the rest of us – why not team up? Betaworks participation means the innovative organization will be able to promote the apps it funds and builds. That’s a strong team to get on board with to promote apps of your own.