iOS: One of the cooler features in iTunes is how it queues music when you're making playlists on the fly. The iPhone music app sadly doesn't follow suit, but Mezzo is an app that brings that style of playlist creation to iOS.
Mezzo is a full featured music player where you can easily play music, check out full screen artwork, look through albums, and everything else. What sets it apart is a solid queue management system where you can instantly add songs to the queue with a swipe, then easily drag and drop songs to rearrange the queue.
It also has some handy swipe controls so you can control your music without looking at the screen. Mezzo is free to check out and you can remove the ads for $2.49.
Mezzo (Free) [iTunes App Store]