Just a few Adventure mode suggestions, I'm sure most have already been suggested.
1. Kill tally accessible from the status menu for the player character and party members.
2. A litany of titles, gained from completing a number of quests in a town.
For example, to gain a title, one must complete all quests within a town, which must be more than 5.
A hero can also gain titles from completing all quests in the Castle, which gives them a national title.
The title would follow the following format:
The [adjective] [hero type] of [town or country name]
So for example "The Glorious Defender of Goat's Bay."
Or, "The Bloody Saviour of the Hairy Empires"
3. Once scarring is in, perhaps it should get worse if that body part keeps getting mangled.
4. Jumping, distance based on size and agility. This kind of becomes necessary when it becomes possible to have otherwise unbreachable chasms in a fortress now that multistory drops are possible. The distance should vary slightly each jump, so it should be possible to fall down the hole instead of making it across.
5. If traps cannot be disarmed, it should be possible, at least, to mark their presence. It should be possible to write a note to recall what a particular lever does, or whatever, especially if exploring another player's fortress.
6. Swimming should be a skill. Actually this should be in both modes. Dwarves could gain it in fortress mode by practicing in pools. Armour would make it increasingly difficult to swim.
7. Ruins with Dragons in them should have a main chamber as the place where they are usually found. This should have a hoard of precious objects, filled with bones.