How do I find all the foreign keys in a database?

SELECT
    FK_Table  = FK.TABLE_NAME,
    FK_Column = CU.COLUMN_NAME,
    PK_Table  = PK.TABLE_NAME,
    PK_Column = PT.COLUMN_NAME,
    Constraint_Name = C.CONSTRAINT_NAME
FROM
    INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS C
    INNER JOIN
    INFORMATION_SCHEMA.TABLE_CONSTRAINTS FK
        ON C.CONSTRAINT_NAME = FK.CONSTRAINT_NAME
    INNER JOIN
    INFORMATION_SCHEMA.TABLE_CONSTRAINTS PK
        ON C.UNIQUE_CONSTRAINT_NAME = PK.CONSTRAINT_NAME
    INNER JOIN
    INFORMATION_SCHEMA.KEY_COLUMN_USAGE CU
        ON C.CONSTRAINT_NAME = CU.CONSTRAINT_NAME
    INNER JOIN
    (
        SELECT
            i1.TABLE_NAME, i2.COLUMN_NAME
        FROM
            INFORMATION_SCHEMA.TABLE_CONSTRAINTS i1
            INNER JOIN
            INFORMATION_SCHEMA.KEY_COLUMN_USAGE i2
            ON i1.CONSTRAINT_NAME = i2.CONSTRAINT_NAME
            WHERE i1.CONSTRAINT_TYPE = 'PRIMARY KEY'
    ) PT
    ON PT.TABLE_NAME = PK.TABLE_NAME

Source : http://sqlserver2000.databases.aspfaq.com