Personal Finance blog Funny About Money tweaks the concept of a "freedom account"—a single stash for irregular-but-common expenses like car repair and clothing—and comes up with targeted accounts. That means opening up a money market or similar small account for each kind of expense, based on how often it occurs, rather than track a bunch of expenses from a big fund.
For example, I look to the irregular little surprises that can happen at any time (plumbing or car repairs, vet bills, etc.), annual expenses (car and home owner's insurance, property tax, income tax), and long-term expenses (purchase of a new car, about once every ten years; major repairs or renovations on the house, which I hope don't happen more often than about once every eight or ten years).
That way, the author states, big walloping expenses like car repair don't throw off your budget and give you a clearer view at what you're spending.