For every item swiped from a plane, there's an eager collector waiting to bid for it. Each day on eBay, travel memorabilia swap hands from TWA napkins of the 1970s to a large array of Concorde crockery and pepper pots. Judging by the amount of stuff available from the retired supersonic service, it's a wonder that British Airways didn't terminate it sooner due to a lack of cups and plates.
Travel is an area of collecting that can involve large sums of money (a Concorde nose cone was sold at auction for $550,000 to a U.S.-based...