Here's a thought on an exotic investigative ability for your GUMSHOE game. It's more of a metagame ability, so it probably won't be for everyone.
You are just lucky. Twists of fortune tend to work in your favor, leading you to stumble over clues everyone else missed.
At any time, you can spend a point of Lucky Breaks to gain a core clue. The GM can and should refuse this spend if someone else has an appropriate ability and seems to be on their way to gaining the clue anyway. Lucky Breaks is not meant to step on the toes of more dedicated investigators. But if the group finds themselves stuck in a scene, feeling like they haven't gotten the important information but unclear on how to proceed, you may just need to spend a point to clear the logjam.
In addition, you may spend Lucky Breaks for other benefits, such as...
- Spending a point to allow a second try following a failed Preparedness test. If this second test succeeds, you find the item serendipitously.
- Changing the set dressing, perhaps at a discount.
- Spending points 1-for-1 to gain a bonus to Hit Threshold against a single attack. You can choose to spend these points after the GM has rolled the attack and declared the result.
Because of its flexibility and power, Lucky Breaks costs two build points per point of rating, both at character creation and with points earned during play.