I'd like to have some statistics after death. Nothing against the tombstone, but it's always nice to get some additional information, like "Number of potions consumed" or "Number of Diggles slain". This could also be used to list some secondary challgenges that the player has done, like "Never used a wand" or "Tithed 1000 pieces of Lutefisk" (I'm no roguelike expert, but I think the appropriate term for that is "conducts"). Not really something I could not live without, but I think it could be a nice addition in some future patch.
On a related note, I get a lot of enjoyment out of persistent data tracking in roguelikes. Like the "monster memory" in Angband or the simple stats text file in Spelunky (which is rogue-ish anyway). It'd be fun to see how many times I've died to each enemy. The Steam achievements already seem to track the number of diggles killed between characters, so why not expand on that feature with some more statistics? That kind of stuff can be quite fun to look at over time. For instance, I'm quite proud of my one death to a chicken in Resident Evil 5.
