The one highly visible success of the stimulus bill has been the cash-for-clunkers program. It induced a boom in vehicle sales this summer that clearly would not have happened otherwise. The rest of the stimulus bill has created a lot of jobs — 700,000 to 1.5 million, according to economists’ estimates. But it has done so in thousands of little ways: scattered construction projects, plugged-up school budgets and the like. Politically, these measures are not popular enough to create a groundswell for more of them. And the economy still needs help. So White House officials are now looking at creating...