Having sound and other multimedia has been mentioned elsewhere but a simple MIDI option would be much appreciated by me
Many smaller churches (and some not so small) who have no organist (and whose tradition does not use worship bands) struggle. A popular option for them is to use MIDI but currently this would require a two PC setup and several pairs of hands for leaders of such churches
PowerPoint allows a MIDI file to be embedded in a single slide and for the presentation to continue whilst the file is playing. Using timings a la PowerPoint (or better still the wireless remote control mentioned elsewhere - SmartDisk make a very reasonably priced product called Power Play) a similar facility in ZionWork would be a killer app. Everything could be handled by one person (the one leading the service probably) and there would still be at least one hand left to do other things
Realistically, not all churches have lots of people to do things