The ACLJ (American Center for Law and Justice) has started a petition to defund Planned Parenthood, and support Senate Bill 351 (S.351), the Title X Family Planning Act, which basically prohibits federal funding to any organization that performs abortions.  Sign the petition (over 10,000 people have so far), and if you are not convinced, try reading the succinct (2 page)  Planned Parenthood Revealed (PDF).