If you are looking for a music resource for your church or home, then Timeless Truths has a free online music library.
The music library has sheet music, lyrics and a song player for hymns and other christian songs that are in the public domain.
The sheet music is available in PDF format allowing you to easily view it and download it.
It also has a handy search function where you can search on song title and song lyrics. The songs are sorted into subjects and you can view them by subject. This is handy if you are looking for songs to compliment a theme or a message. For some of the songs you can listen to them in midi or mp3 format.