For MTTs, I've found it worthwhile to keep track of a couple of things beyond just the amounts I've won.
- ROI for buyins (requires tracking tournaments entered, cost for each one)
- win rate per hour for freerolls (win rate per hour per tournament would be better in order to account for multi-tabling, but would involve keeping more detailed records than I'm willing to do).
I know other people track the percentage they finish in the money. I haven't gotten around to trying it yet, so don't know if it's worth doing or not.