One of the leading worship presentation software providers is MediaShout. They have been around for a long time and I was able to speak with Paul Jackson, one of their founders at a recent conference I was at. That interview is available on the WELSTech Podcast, Episode 35. They have an Express version which has a smaller subset of functionality for a cheaper price, but might meet the needs of the average church. You can also upgrade to the full version for not much more than the full price on that. There is a comparison chart between the full version and Express version here. The cost of the full version is $429 and $229 for the Express version. The features of the full version include:

• Total control: dual-monitor design ensures that the audience sees only what you want them to see
• Song lyrics: display the words to any song in any order
• Bible passages: select and show any passage instantly, in any of 52 versions
• Text: create and present announcements and message points ... or use a virtual blackboard for instant, live text
• Video: no tapes, play video files, DVD clips and external video feeds on their own or as backgrounds to other cues
• Graphics: display photos, illustrations, drawings, maps, and more
• Animations: play Flash files on their own or as motion backgrounds for lyrics, Bible verses and other text screens
• PowerPoint: play PPT files straight from MediaShout without switching programs
• Web pages: display web pages full-screen to the audience
• Sound: play music, sound effects, MP3, MIDI and more