More retirees and senior citizens are taking part-time jobs than ever before. According to the U.S. Bureau of Labor Statistics, participation rates in the workforce among people 65 and older are expected to increase through 2024. Some seniors need the income for living expenses. Others want to supplement their retirement savings or invest in future generations. Still others just like the activity and socialization. If one of those scenarios describes you, check out these lucrative, fulfilling opportunities.