Ostensibly, Songbird is a free music player and library.
There are already a slew of free music players with library functions available, some by commercial giants like Apple and Microsoft.
Songbird even bears more than a passing resemblance to a rather famous example of the above: it has a big library window in the middle, search tools, digital file conversion features, playlists and even the equivalent of iTunes' Genius feature through a third party recommendation engine.
It is, to all intents and purposes, an open-source version of iTunes. But it's the phrase 'open source' that is valuable here. While iTunes only connects to the iTunes Store when searching for music that you want to purchase, Songbird also searches Amazon's downloads store and other sources.
Its open architecture means that new functionality can be added using plug-ins, including tools that scrape free MP3 blogs and present them in a window for easy download. All this makes Songbird well worth a try if you want more flexibility than iTunes currently offers.