It would be nice if the program calculated USGA handicaps. There's a lot of potential here.
It would maintain and update handicaps from round to round. Method here (http://www.usga.org/playing/handicaps/manual/handicap_system_manual.html). Looks like a lot, but is actually quite easy.
It would show course handicaps and hole-by-hole stroke allowances for each player.
It would allow posting of both 9-hole and 18-hole scores. Per the USGA system, two 9-hole games can be combined into an 18-hole round for the purposes of calculating the handicap differential. The system would have to hold back a 9-hole score until another 9-hole score is posted.
This would require adding Slope and Rating info to the courses, as well as calculating handicap differentials after each game. It would also require entry of Slope and Rating for front 9 / back 9 sections of each course for proper calculation of handicap differentials.