If you did want to add more data fields to the statistics:
* Count of number of items picked up (or used, for powerups / AoI), dropped, destroyed by player fire, monster fire, barrel; generated, left behind (still on level when descending).
* Total monsters generated, also per type.
* Counts for monsters revived by arch-viles, and by being on N!.
* Total floors visited.
* Total special floors visted (or count for each one).
* Total # tiles illuminated (Would also allow a global exploration percentage).
. . .
I'm out. People already mentioned barrels exploded and levers pulled and such. Maybe add barrels generated and levers generated. (I could see things to go for in a mortem being 100% of exporation, levers, barrels killed, etc, just for fun.)