Amarok, with RhythmBox, is one of the two most popular Linux-based music playing programs. Amarok was designed to work on KDE-based systems, but should run quite happily on a GNOME-based system. I had some annoying problems with it on an Ubuntu laptop, but your mileage may vary.
Amarok may come with your distro by default, but if not it can be installed via the Applications / Add & Remove Programs menu item. Alternatively it can be downloaded from amarok.kde.org. Support is also available from this site.
Because of legal restrictions it might not have MP3 codecs installed, so if you want to be able to play and rip MP3 files you will need to install these separately. These should appear in the Add Programs box under the name ‘GStreamer extra plug-ins’, but in any event a search for ‘MP3’ should locate them.
Amarok opens into a window with a vertical set of tab buttons at the left. By default these are Devices, Magnatune, Files, Playlists, Collection and Context, but some of these can be omitted via the ‘Manage tabs’ button directly above them. Clicking on the tabs changes the window display as follows:
Devices – shows attached music players and allows the user to drag and drop files between the player and the playlist. I was unable to get this working on an Ubuntu installation.
Magnatune – links to the Magnatune music distributor.
Files – allows the user to browse through directories looking for music files to play. Files that are found can be appended to an existing playlist.
Playlists – allows the user to create, save and rename playlists by dragging tracks from the collection or by defining a list through criteria. This feature – called ‘Smart playlists’ – allows the choice of files on the basis of title, artist, album, length, when they were last played and so on.
Collection – shows the entire collection of tracks sorted by artist and album. Context – shows details of the playing track, including an album cover, lyrics and Wikipedia information about the artist if these are available. Album covers are retrieved from Amazon and lyrics from an online lyric database.
In the Amarok playlist window tracks appear at the right. They can be sorted by any column, and the column display can be changed by right-clicking on a column heading and choosing ‘Select Columns’.
Amarok screenshot 
