You can also sometimes find free music in your "ward library" or "stake" music library. Also the lds choir songbook has about 20 songs of pretty good quality.
See also a list of choir conductor resources.
Also we know of a few resources for arrangers:
http://ldsmusicwriter.com/2011/09/advice-from-jenny-phillips/ (and her other blog posts) for composers advice on how to write lyrics etc.
Peter Covino offers "music editing and [computer generated] recordings that are not only correctly notated but you can actually hear the voicing and instrumentation.
People that will allow you to "commission" a piece/work from them: M. Ryan Taylor and Nathan Howe and Michael Hicks, Amy J. van Dyk Allan D. Osgood Jeff Combe and probably others (ping me to be added to this list).
http://www.sugardoodle.net/joomla/index.php?option=com_content&view=article&id=3873&Itemid=200060 has some good resources.
Also a big thanks to people who have let us index their songs
See the current list
Here is a list of all the other LDS composers/arrangers we've been able to find out there on the net.
If you know of another not listed, please tell us!
Some sites are pay, some are free, some are SATB, some are piano. There's a lot of us out there!
FFmpeg is a great command line video conversion utility. You can download ffmpeg windows builds here.
Other LDS sheet music sites we haven't yet indexed, but hope to soon (some are pay):
blueskies.itgo.com/sheet.htm www.rosalindmlukecrosby.com/index.php?option=com_content& view=article&id=61&Itemid=60
You can suggest other links for us to add here through the contact us link at the bottom.
online music lessons [pay, mostly just in french music lessons]