As the spirit of giving wraps up this last week of 2010, here's some food for thought: Research suggests generosity is good for you. New studies attest that giving benefits not only the recipients but also the givers' health and happiness, while bringing strength to entire communities. Of course, you don't have to shop to reap the rewards of giving, the same benefits can come from donating to charities or volunteering time to a good cause. UC Berkeley's Greater Good Science Center offers up 5 ways giving is good for you.