my wife has a spending account (she calls it her slush fund) that she deposits about 0.5% of her paycheck into. she does whatever she wants with that money and i don't say anything. it comes out of her paycheck and gets deposited into a separate bank account automatically, so i don't even notice it.
i manage the money in our household, so i don't have a spending account for myself, but it probably would be a good idea. the idea behind the spending account is two fold. it puts a pause into our spending habits. if there's some impulse purchase that we want to make, it comes out of our spending accounts. if we don't have enough cash on hand, we'll have to make other arrangements (save, reconsider, haggle, etc.). what it really does, though, is gives each of us the freedom to buy something that the other person may think is a waste of money. it doesn't impact our bottom line and it kills any arguments before they start.