There are several music databases on the web that you can go browse and look and information related to music. Some include the Gracenote CDDB, The All Music Guide, FreeDB and MusicBrainz. What are the differences between them? I've posted about the CDDB and All Music Guide before. Both of these databases are used frequently by the musicians I work with and around every day. You can read more about them by clicking these links.
MusicBrainz is a community-maintained open source encyclopedia of music information. They started as just a database of audio CD's and have now made thier database to include information about all music, regardless of release format. With more and more digital releases, this seems like a great idea. Also, the database is relational. That means all albums by a specific artist can be grouped together. The database is also open source (that means free). If you want to write software that plays music, you do not have to pay a licence to access the database and retrieve metadata for the files your program will play.
If you are releasing music and would like your stuff in the database, you can go sign up and start adding your releases to the database. This way, your music will show up in programs that use this database to retrieve metadata. Just sign up for an account and edit away. Also, if you have a large music library on your computer that needs correction or editing, this database can help.