Encumbrance - I don't like long tallies and making players add and subtract how many .1 pound units they are carrying. But I do like players making decisions. What is important to bring to the dungeon and what has to be left behind? And even more importantly: what treasure is worth lugging out of the dungeon? Here's a huge chest full of gold, but it'll take two dudes moving at 3" to get it out. Are those coins worth the 6 extra wandering monster checks between here and the surface?
Rations & Wineskins - I've seen (and run) lots of games where the PCs buy rations and wineskins at chargen and then everybody forgets about the whole issue. Wearing armor, carrying a crapload of equipment/treasure, and fighting ten times a day is going to burn up a lot of calories. I recall reading somewhere that troops in combat zones can be expected to go through six M.R.E.'s a day. I don't have any combat experience but I know that after a hard day of moving furniture or playing sports or whatever that everyone wants to chowdown on pizza and guzzle beer.
Colorful Fights - I usually don't need the rules to encourage me to buckle swashes, but sometimes players can use a little reminder or a push in the right direction. Perhaps something simple like Lucky Number Kung Fu, whereby every once in a while they get some sort of extra action with which they can be awesome.
Filth - After a long day in the dungeon everyone will probably come out with torn clothes, dried blood on everything and smelling like a dragon's latrine. Any self-respecting adventurer probably gets a bath and a new suit of clothes the moment they get back to town. A lot of equipment probably needs to be replaced, too.