Could be off here, but from a look-see at this point, Pitt 24-20 is the most popular (with 5 people choosing it).
Also popular is GB 31-27 (3 times) and there are 8 scores chosen twice (including GB 28-17 above, which occurs on post #19).
I'm going to go with GB 28-26 (which seems to not be chosen yet - Pitt will try to tie with the 2-pt conversion at the end, but will miss, or something completely different will happen, I'm sure.)
The reason that Pittsburgh 24-20 is the most popular is because it's the Madden NFL simulation prediction. Packers 31-27 is also another prediction...
People are lacking the skill or brains to actually pick numbers, so they're just taking professional predictions and using those as entries.