Band Music
It's pretty enjoyable when a band/team plays music well 
even more so after especially difficult and gruelling practises.
Always felt that the skill of listening whilst playing can never be learnt/practised when playing alone, though it has to be exercised consciously.
That said, "perfect" playing is not the be all and end all for congregational use, though it's not something to be taken as unimportant altogether in serving.
Teaching kids real math with computers
Math (and its education) has always been a topic of great interest to me, since it's the underlying workings of so many things we encounter out in the real world. In his TEDTalk, Conrad Wolfram (who runs Wolfram Research) argues for the case of keeping math education in line with the times: using computers to do the calculations as we usually do in real world applications, and focusing education on understanding the underlying concepts mainly. The comments sure add a whole lot more depth to the topic at hand, be sure to take a look at them too!
[via TEDTalks]