First, check your state's programs. The American Federation of Teachers at AFT.org has a tool to check every state to see what programs are available to forgive student loans by becoming a teacher. The amount of debt forgiveness varies.
If you have received a Stafford Loan after October of 1998, you can be eligible for up to $17,500 to pay off that loan by teaching in a designated school for five years. More information is at StudentAid.Ed.Gov.
If you have a Perkins Loan, 100% of that may be forgiven if you teach at a low-income school designated by the U.S. Department of Education. Visit StudentAid.Ed.Gov for more details.
Teach for America, part of AmeriCorps, will give you $9,450 after two years of service to pay your student loans. Visit TeachForAmerica.org for more details.