There are more than a few music players available for Android, but you could search the Play Store for days without finding one quite so full-featured as Music Player (Remix). The developer seems to have thrown every possible bell and whistle into the local playback app, and topped it off with a swipe-based interface and some impressive extras. It's available in the Play Store for $4.99, with a 14-day trial app available as well.
The core app is fairly typical as far as music players go, with some playlist management that's particularly interesting. The interface is based on swipes: swipe up from anywhere in the app to view the Now Playing screen, swipe from the right for your library, and swipe from the right for playlists and favorites. The Now Playing screen gets a bit of customization with five assignable shortcuts for functions like lyrics, bookmarks, sharing, and even a quick link to search for the song on YouTube.
But what we're most impressed with is the pop-up control system. From anywhere in Android, you can swipe up from the bottom of the screen and open the Mini Player, which includes playback controls, track seeking, and full playlist management. It's a full-featured player, much more powerful than the typical notification controls. Just swipe down to hide it again. (If the whole swipe-happy UI seems familiar, you might be a former WebOS user - this app was a favorite on ye olde HP TouchPad.) The video below shows off all the feature of Music Player (Remix), but if you want to see the nifty Mini Player, start at 4:35.
The app includes a ton of other features, like a full tablet UI, homescreen and lockscreen widgets, Last.FM scrobbling, lyric and art fetching, expandable notification controls, auto-generated playlists, and even an in-app Wikipedia browser. Bookmarks within songs can be placed manually, or appear when you exit. (This is great for audiobooks, by the way). In short, Music Player (Remix) is worth the $5 price of admission.
Thanks to developer Hedami for the tip!