When itunes just doesn't cut it...
I'm a sucker when it comes to mellow music (can I say this 'sucker' or is this considered as explicit?). I really am. You just go and try getting a smart playlist that gets all the soft, slow music together. It doesn't work. Ditto when it comes to the opposite. Any 'mood' related playlist really. But Tangerine! succeeds in a very original manner.

App name: Tangerine!
Developer: Potion Factory
Promotion in podcast: yes (go check out the episode... you don't want to miss this)