+1 for the accurate club. Using an Excel worksheet, I know what I bought, Where I bought it, how much it cost, how much I have, how much I've used in which guns, malfunction count and type, and cleanliness.
And yes, I even fill out a shooters log at the range so I know where to sight in different rounds.
I do not consider myself anal, just a mathematician.
I use an Excel spreadsheet too. Track:
Shots fired, by gun and location
Inventory; caliber, weight, type
Purchase price (gross) per round.
Why? What difference does it make? Whether you admit it or not, it's anal. I wager that you keep spreadsheets on the gas you use in your car, your electricity used and probably how many bulbs are on your Christmas tree.