gtkpod is a platform independent GUI for Apple's iPod using GTK2. It allows you to import your existing iTunes database, to add songs, podcasts, video and cover art and to edit ID3 tags. gtkpod also features international charset support for ID3 tags, detects when adding already existing songs, and more.
Many new features have been implemented with this release: multi-threaded on-the fly conversion of WAV, FLAC and OGG files to formats the iPod understands, background-copying of tracks to the iPod, display of album art, download of album art and preliminary support gapless playback for MP3 files.
Many bugs have been fixed along the way as well. Have a look at the changelog