Music. There are some websites that offer musical selections that are either public domain (the copyright expired — many older hymns fall under this category) or they are original pieces of music that are given away freely as a ministry. Here are some free resources to try. Please be considerate and follow the website's usage instructions:

http://cyberhymnal.org
http://songsofpraise.org
http://members.aol.com/alshymns/godsmusic.htm

If you want to use popular music found on a CD or heard on the radio, you'll probably be required to pay royalties every time someone visits your site. For more information, please do a web search.

Images. You can either use original photos and artwork, do a search for freely available original artwork, or purchase images from a stock photo house such as Corbis. Here are some sources for free images. Please be considerate and follow the website's usage instructions:

Clipart: http://www.designedtoat.com/freegraphics.htm
Free stock images from Stock.xchng: http://www.sxc.hu/
Photos offered by the National Oceanic and Atmospheric Association: http://www.photolib.noaa.gov/
Professional quality "retired" stock photos. Use the search feature to find what you need: http://www.morguefile.com/