We, the United States of America, should buy Mexico.
It could be like Puerto Rico. Think of the money we'd save on border patrol and immigration issues.
Sure, there'd be a big investment and a lot of work and money spent for awhile getting things set up (catching drug lords, etc), but after that there'd be a smaller border to worry about (Guatemala and Belize) and the efficiencies of trade, travel, vacation, labor, etc. would begin to pay off. The United States is already Mexico's largest trading partner (http://mexico.usembassy.gov/eng/eataglance_trade.html)
Yes it's crazy, but less crazy than billions of dollars spent on a war looking for non-existent weapons of mass destruction.