Aggregator Sites:  One-Stop Shopping? When Che Carsner wanted to find discount airline tickets for his parents from the Miami area to New York, he knew where to look. The Manhattan real estate agent logged onto Kayak.com, a new online travel aggregator, and typed in some dates. Within seconds, dozens of options appeared. Among them: a \$140 round-trip fare from Fort Lauderdale, Fla., to LaGuardia airport on US Airways, which he booked.