Workers aged 50-70 are increasingly returning to the workforce after retirement. The main reason that people return to work are financial need and boredom. Agencies like the National Able Network provide job training, counseling and placement services to help seniors find employment. Companies often look to hire older workers who they feel have many desirable skills and qualities.
See "Some finding retirement is only a temporary state", Karen Schwartz, Chicago Tribune, March 16, 2004