NIFE now tracks damn near everything players do in the game via something called the Experience System.
Normal Things that are tracked
Every single action, present and future
Each sparring action (a lot of plugins treat sparring actions as a group, but this tracks things like "flee" separately)
specific machine type interactions (replicator, item switch, etc) are individually tracked
Interactions with machines in general are tracked
Successful / failure interactions with item switch, combination lock, replicator, transmogrifier machines are tracked.
Crafting from an existing recipe
Trial-and-error crafting success
Trial-and-error crafting failure
Trial-and-error scrapping success
Trial-and-error scrapping failure
Miscellaneous tracked stuff
Any time you die
Any time you kill another player via the sparring system or the reflex system or any future PVP systems
When you offer an item to an NPC and it's the thing they're looking for
When you reload a weapon successfully (via using the correct ammo box)
When you summon successfully (implies you have enough of the stat that you spent)
When you successfully open up another player's inventory so you can steal from it.
Each time you buy an item from a shop (amount goes up for each item in a purchase, not each purchase)
Each time you sell an item to a shop
Each time you change your equipment
Each time you activate an item trap that hits you (ouch!)
Each time you activate a character's reflex and they automatically attack you
In addition to the work above, the system is set up so that I can add experience hooks to pretty much anything you want to add them to. I don't want to do this explicitly with everything because it would take weeks, but you can request that I track some function or some filtered thing and I can add it in a matter of seconds.
Characters attacked with an item with a specific trait
Mines whose products are in a specific category
Track the number of times a player switches to a minion they're leading
Player Statistics plugin
There's a new plugin in the "information" section of the add/remove plugins area. Activating it will give players a little panel that then pulls things out of the experience system:
As you can see, it's very rudimentary, but should be useful for testing purposes if nothing else.