What's a good iPhone app for playing my own music files offline, especially when I'm out on a job site with no signal?

Look, I'm a practical guy. I don't need a bunch of bells and whistles when I'm trying to listen to some tunes while I'm overseeing a construction project. Melodista Music Offline Player does exactly what it says: plays my music offline. I've got a ton of MP3s from way back, and this app handles them no problem. The interface is straightforward, nothing fancy, which is exactly what I want. No constant buffering, no data charges eating into my bottom line. Plus, it's saved me a ton on data costs. For a simple, reliable offline player, this one's a winner. It's not gonna win any design awards, but the ROI is solid – it just works, and that's what matters to me.