I've thought about doing this because my students loans are crippling...
From the Direct Loans website (if you have Federal Direct Loans):
Teacher Loan Forgiveness Program
The Teacher Loan Forgiveness Program was instituted by the U.S. Department of Education to allow borrowers of Direct Loans or Federal Family Education Loan (FFEL) loans to have up to $5,000 discharged from their student loans. Direct Loan borrowers who are teachers with new loans after October 1, 1998 and who are teaching in selected low-income schools for five consecutive complete academic years may be eligible for the Teacher Loan Forgiveness Discharge.
Teacher Loan Forgiveness Site