2. The sharp airline rally Along with makers of pick-up trucks, transportation firms and operators of cruise ships, no industry would be more pleased to seeing falling crude oil prices like airline carriers. Jet fuel is their single-biggest expense, and by some estimates a $10 drop in crude oil pumps up industry profits by more than $1 billion. The Dow Jones U.S. Airlines Index, which has fallen from 120 in 2007 to a recent 70, looks poised to be one of the top performing indexes of the next six months. It's not only about falling fuel prices. Companies that operate leisure parks such as Walt Disney ( DIS), Six Flags ( SIX) and Cedar Fun ( CF) have traded up to 52-week highs in recent sessions as vacation spending spikes higher. The Obama administration recently streamlined travel regulations and visa requirements for foreign visitors, which has set the stage for a banner year for tourism. Analysts at McKinsey & Co. note that if foreign travel to the United States rebounded to pre-9/11 levels, when it became much harder to get a visa, then the U.S. economy would receive a $214 billion annual boost. Airlines will play a key role in bringing those tourists over. 3. The U.S. economy slumps in the summer but surges in the fall The U.S. economy is clearly slowing as the weight of depressed trading partners starts to drag us down. U.S. manufacturing activity dropped in June to its slowest pace in three years. Other economic surveys such as the CFNAI are also flashing concern. As a result, second-half outlooks from many major companies could be downbeat enough to bring stocks to their lowest levels of the year. Yet, there are seeds of hope. Recent events in Europe will likely help to avert any major crisis in the near-term, and the Chinese government is now stepping up its own stimulus efforts. As a result, many key players in the European and Asian economies that had been holding back on orders for fear that economic events will spiral lower will likely shift gears. The pent-up demand could yield to a snapback by the fourth quarter, which will likely boost the U.S. economy later in 2012 and into 2013.