NimbleBit, the creators of the hugely successful Tiny Tower game for iOS, are working on their next title called Pocket Planes.
You'll recognize the adorable 8-bit graphics right away, but this game looks like it will be much more involved than Tiny Tower. Pocket Planes will be more of a time management and resource investment game similar to Now Boarding ($1.99 - Download now); you manage your airline staff, coordinate flights, load up passengers, and get them to their destination. With the money you earn, you can buy new planes, hire new staff, and open connections to new cities.
What's going to make Pocket Planes deeper than Tiny Tower (which boiled down to a simple and addictive restocking game) is that the planes have a ton of statistics on range, speed, cargo capacity, and offer a lot of customization in terms of paint jobs, pilots, and costumes for those pilots. This opens up a lot of gameplay variety. For example, you could have a bunch of small, regional pockets offering speedy commuter service within certain regions, or you could skip passengers altogether and focus on delivering cargo instead, or you could go for distance, and invest in expensive long-haul airplanes. Given the number of cities you'll be connecting, the flight network could very quickly - especially once your airline expands overseas.
Pocket Planes is still a work in progress, so all of this is subject to change. Even if they end up ditching the in-app purchasing mechanism, I'd be willing to shell out a few bucks for this title when it lands this summer.