Very interested in [Preparedness]. How does it work? Maybe I can port it to other games.
GUMSHOE defines each character's skill as a set of pool points. Players spend from the pool to make it easier to over come a target difficulty. So
Preparedness is a skill a player has and may have pool points in (generally from 0-10 or so, but 12+ is not uncommon for higher power games).
The skill works like this: When a player thinks of some piece of equipment they would like to have at this point in the game, but didn't explicitly mention, they can make a preparedness check to have it, with the difficulty being set by the GM. In GUMSHOE the dice used is a d6, so a difficulty of 4 is the standard -- a 50-50 chance of success if you do not spend.
As a GM, I would make the difficulty of something 2 if it's something they really ought to have, but might be fun if the didn't remember to bring it; 4 if it's something they might have brought, 6-8 if they would have needed very clever forethought to have it, and higher if it would be essentially an amazing stroke of luck. Recall that a pool of size 6 is quite normal, so players could spend 3 and only need to roll a 3 on d6 to hit a difficulty of 6, so the game does aim at hyper-competent people. This skill's pool refreshes between scenarios -- not sessions -- and I tended to run 2-3 sessions per scenario, so people would spread it out a bit.
If I was adapting this to d20 games, I might try something like this:
Preparedness. Make a check to determine if you had prepared by bringing an object you describe with you. The GM will set the difficulty based on how available the item is, and how likely i would be for you to bring it (so bringing rope to a mountain-climbing expedition would be trivial, whereas bringing ancient history books to a bar might be hard). If you fail the check, you expend one use of this skill. The skill has a bonus provided by INT, and the number of uses per day is equal to your WIS bonus, minimum one.
Feat:
Ready for Anything: You have a +5 bonus to Preparedness checks, and once per day may re-roll the skill check.