Many states are cracking down on the use of cell phones while driving. In fact, just across the state line where I live, using a cell phone while behind the wheel can get you stopped by the State Police and fined (no matter what you are doing with it). Wheeltunes($0.99) aims to make at least the act of accessing your playlist or controlling your player safer with a fully gesture-based player control UI. However, it is important to note that it still likely can't protect you from a fine. You should make sure to know the cell phone driving laws in your home state or anywhere you may be traveling this summer, and follow the law. If you must drive and play with your music player, you certainly should do so with an app that has a simple, stark interface and allows you to change tracks with a swipe.
Safety and legal issues aside, I must say, WheelTunes is great for anyone looking for a simple player app design. Personally, I think its developer, Picmoo, should emphasize its design instead of just the driving feature. Driving with a smartphone in your hand is not yet illegal everywhere, after all.
Since the app is so basic, so will this review will be basic as well. You start up WheelTunes, and start swiping through your song lists. A single screen tap starts or stops a track, and a swipe left or right changes tracks. I could not seem to find a way to slide back and forth incrementally in a track. A long press on the screen with a slide lets you adjust the volume up and down. Unfortunately, not everything is gesture-based. If you want to access playlists, albums, or artists, you swipe up the main screen to a navigation menu system, though it does tend toward large icons/text and a similar high-contrast theme. Overall, I like the austere look and feel of WheelTunes.
If you need a music player that keeps you from constantly squinting at your phone, WheelTunes nicely gets the job done. I would add, support for skinning other player services like Pandora or Slacker (a universal player app, if you will), though I understand that could be onerous from a coding standpoint. I would change the name and add some unique feature to the app that will make it stand out from any similar gesture-based player apps (of which there are a few on the App Store). I might add a Siri-like voice integration that announces a new playlist, artist, or song when navigating via gesture.
Pros
Easy-to-use player controls
Cons
Menu system still required