gtkpod is a graphical user interface to upload and manage songs to your iPod. 

It allows you to :
    * Read your existing iTunesDB (i.e. import the existing contents of 
      your iPod).
    * Add mp3 and m4a (no-protected AAC) files (single files, directories or
      existing playlists) to the iPod. You can choose the charset the ID3 tags 
      are encoded in from within gtkpod. The default is the charset currently 
      used by your locale setting.
    * When adding songs, gtkpod detects duplicates (option).
    * Remove songs from the iPod.
    * Create and modify playlists.
    * Modify ID3 tags -- changes are also updated in the original file (option)
    * Refresh ID3 tags from file (if you've changed the tags in the original
      file).
    * Sync directories.
    * Normalize the volume of your tracks (uses mp3gain)
    * Write the updated iTunesDB and added songs to your iPod.
    * Work offline and synchronize your new playlists / songs with the iPod
      at a later time

WWW: http://gtkpod.sourceforge.net