Power Amp for Android. All I can say is "what took you so long". It's still in beta and is so superior to anything out there it's crazy. Not on the Market yet but you can read about it here (
PowerAMP is looking amazing! - xda-developers) and find the download link in the story. I used to use Mixzing (paid) but this really blows it out of the water. Scans all 500 + music files on my phone in 0.49 secs. Puts them in a cohesively organized fashion and if you are an audiophile like I am then don't delay. This sounds fantastic with customization for any music lover. Has an equalizer and pre-amp. Using this with my Boston Acoustics sound system in my truck makes me not want to get out. Looks good with a couple of skins and has a widget, tags and lyrics. Can't say enough good stuff about it. Not the best at downloading album art but no worse than Mixzing or Music Mod and if you already have the art you should be golden. Try it! This is a beta though but I honestly LOVE it and think it's the best out there right now.