If you use iTunes to manage your music, then you know it's handy but has a few significant limitations. Fortunately, the open source community has come to the rescue with some great little apps designed to make using and working with iTunes a little easier and less frustrating.
Firefly Media Server - Here's a great little tool from sharing MP3s across your network with any computer running Linux, Windows, or Mac OS X. It has support for dynamic or static playlists and a Web-based administration dashboard for easy access from anywhere. In addition to working with iTunes, Firefly Media Server also integrates with the Roku Soundbridge to play music right through your stereo system.
iLeech - Although it's possible to stream music to other computers on your network with iTunes, you can't copy your music files onto another machine with it. With iLeech, you can connect to your iTunes playlist from another computer and copy files directly onto your local drive. This is a great little tool for making backups of the music you already own in case of a catastrophic hardware failure or some other data loss disaster.
CCTunes - Turn your iTunes music library into an nifty HTML-based list to display on your blog or Web site. Use CCTools to manage or search Amazon.com album artwork, then fill in additional music descriptions and details with its built-in tools.
hymn - Here's a great app that frees your iTunes Music Store purchases and lets you play them on any computer platform or music player with no loss of sound quality. It decrypts AAC files and eliminates the iTunes' five-computer limit, making this a good option for making backups of music you already own or to play your purchased music on all your music devices or computers.
iPodFS - If you want to move your iTunes database to a non-iPod music player, then this app is for you. Use it to display your iPod database on a computer, then access it from any USB-connected MP3 player. iPodFS also lets you access iPOD files via the command line and play them through an MP3 player on your desktop.