Cantata is a (yet another!) client for the music player daemon (MPD). Originally started as a fork of QtMPC, the code is now very different. Cantata can be compiled with KDE support, or as a pure Qt application. The interface is very configurable - most views can be shown as either a list or tree structure.
Ranked in these QuestionsQuestion Ranking
Not only can it help manage a music collection but it also features easily configurable dynamic playlists and support for a variety of audiostreaming sites and digital devices. Also, supports last.fm scrobbling out of the box (not common with mpd front-ends).
Since it is a front-end for mpd, queries within Cantata are lightning fast.
Pro Easy copy to mobile
Right-click to copy an album to your phone.
Pro Excellent for large libraries
Pro Support for ratings
One of the few mpd front-ends that permits ratings to be stored and queried.
Pro Excellent at tagging/renaming files
Guesses tags from what's already in your music directories and renames files to match tag info (if that's what you want).