If the player exits a level within five seconds of entering it, add a line to their history: "He hurried through level X." Mostly to poke fun at the players who homing phase through scary caves or the last few levels. :)
If the player has advanced in rank during a given run, that character's mortem file should reflect the advance. It's kind of lame to pull off a bunch of kills or get enough new medals and then not be able to show the rank off until you've started a new character. Heck, I'd even go as far as to say that rank advancement should be specifically noted in that mortem as a landmark ... something like "He advanced in rank from X to Y!" just above the 'he played for blah blah time' line.
Custom mortem files. By which I mean, a few config options that allow you select which parts of the mortem you do or don't wish to see. I don't feel this is actually necessary at the moment, but the upshot would be that you could then add options to display more arbitrary statistics for curious players. (Like ... a table showing how many of each enemy were killed in each level, or the total number of keypresses made in the process of the game.)