Positive word of mouth always benefits a restaurant. A rave review in the local fishwrap usually helps. But you know what really gets butts in the door? When the Leader of the Free World says your pizza is the best he has ever eaten. President Obama first sampled Pi's cornmeal-crust pies during a campaign visit to St. Louis in October 2008. After speaking to 100,000 supporters under the Gateway Arch, the candidate called Pi owner Chris Sommers and told him how much he loved Pi's pizza. In April of this year, the president invited Sommers to cook pizza at the White House. The trip brought Pi national attention — even more so after some Chicagoans took umbrage at their hometown hero digging deep-dish pizza from another city. (Others criticized the president, claiming — falsely — that taxpayers had footed the bill for Sommers' trip.) Sommers handled the faux controversy with grace and humility. Which is even more impressive when he could have pointed out that, after his trip to Washington, the wait for a table at Pi could be two or even three hours.