Poverty, terrorism threat, cold weather, hurricanes, tsunamis, unforseen events such as contagious disorders, unjustice and unfair treatment, lack of control over own work, difficult neighbours, lack of access to pure water, food, shelter and medication, continuous fear of war, chronic diseases, divorces, belonging to the "wrong" race, illiterate, oppressed by ignorant men, lack of education.
The Trier social stress test is certainly effective and has good ecological validity (the public speaking part, especially for student samples). Although I don't think it has been looked at, it is also very stressful on the unresponsive confederates who serve as the audience.