I've recently become the Guild Master of the Thieves Guild in Skyrim, and I was wondering if the business ledger in the guild had any use outside of cosmetic purposes? I've tried using it, but nothing happens.
These types of ledgers are used in Delvin's "Numbers Job" radiant quests. For this type of job, you'll have to sneak into a business and interact with the ledger in order to change something, which the game generally doesn't go into any consistent detail about.
The one in the Guild proper is not one that I've ever had as a target, even though I've run probably around 100 of these jobs. It kind of makes sense, as editing your own ledger wouldn't make much sense.
Outside of these quests, I've not found a use for it (or any of them) - it's not referenced in any other quest that I can find, so it appears to be strictly cosmetic.