I've actually found double-entry bookkeeping really useful for personal finances. Let's say I transfer money from one financial institution to another (say, a bank to an investment firm). With double-entry, I can track and reconcile both sides ("legs") of that transfer: one positive, and one negative. And they have to match up for things to balance.
Real-world example from my Gnucash file: I buy a present for my friend Alice for say 50$. Another friend, Bob, wants to share half of the cost and promises to give me the money next week.
I can easily [1] represent this as a split transaction where 50$ go out of my wallet's account. Half goes into Expenses:Gifts:Alice, half goes into AccountsReceivable:Bob. Once Bob pays me back, I transfer the money from AccountsReceivable:Bob back into Wallet.
[1] I guess I have different standards of "easy" than most of the population.
My credit cards are each an account that I transfer money to each month. Most of my purchases go on one of my cards and then get paid off each month. CC transactions match that CC account and a category like Expenses:Auto:Gas.
My checking account is pretty much just account "transfers" and an occasional transfer to my "Cash in Wallet" account for ATM withdrawals.
