Facebook has a great, little feature that allows users to play MP3 files inside the site. Links to MP3 files, from status updates for example, are converted to an integrated media player enabling users to listen to them directly without downloading the songs. Facebook-focused blog All Facebook uncovered the feature, but it seems that it may have been available for a while now.

The feature is basic enough and it doesn't require any input from the users, either the ones sharing the link or the ones trying to listen to the song. All a user has to do is post a direct link to an MP3 file, any link ending with .mp3 will do, apparently. When the status update ends up on the site, it will get a simple audio player to preview the track, though the original link is also available.

There are plenty of medial player apps on Facebook and services offering to host MP3s for you. There are also services that allow you to embed songs on blogs or social networks, free music-streaming services like Grooveshark, but this method offers more flexibility.

It may be a little harder to get direct links to MP3 files, though not that many sites are willing to risk a lawsuit for this. You can, of course, host the files yourself, though this may not be the simplest thing to do for most users, not to mention that it may be illegal in most cases.

Still, there are plenty of people sharing their songs online as promotional tools and many music blogs that share and host music files online, legally, though not always without problems. Google also has its own MP3 player it uses on several of its sites and even allows others to embed it. Yahoo also provides an interesting, embeddable player for bloggers and sites to allow users to listen to MP3 files online.