Get a high GRE score. Most PhD programs require that you take the Graduate Record Exam (GRE) for admission. If you show exceptional performance on the test, the admissions committee may overlook your poor grades. Contact the admissions department and ask what weight they put on GRE scores. Ask a representative if there are cutoffs and what they would consider a high score. Consider enrolling in a prep course or using study aids to boost your score.
Strengthen your personal statement. A strong personal statement that shows your commitment to the field can also help your application. If you suffered adverse circumstances that forced your grades to suffer, explain those circumstances in your personal statement. Any civic duties or outside interests that show you to be a well-rounded candidate with broad accomplishments may also help the admissions committee look past your poor GPA.
Volunteer to do research. PhD faculty are usually involved in academic research. Offer your services in their laboratory or research setting. Perhaps you can do data entry, interview subjects or do literature reviews. Even as a volunteer, you are considered a member of that academic department and the faculty member is your mentor. Your mentor may now be your advocate to help you get accepted into the PhD program in that department or a similar department in another institution. If accepted you might continue to do that research as a student. Strong letters of recommendation from people in the academic field you are interested in pursuing can help your PhD application. As a research volunteer, join your mentor or other members in the lab at regional and international conferences -- try to meet other leaders in the field. Investigate other opportunities to volunteer for them in exchange for a letter of recommendation.
Enroll in a terminal master's program. Some PhD programs have a master's program attached to it. Often master's and PhD students will take foundation courses together. If you perform well in those courses you may be able to use your transcript to apply to the PhD portion of the program in subsequent years. You may even be able to get letters of recommendation from faculty whose courses you did well in to support your application. In any case, it will show the department that you are a hard worker who is committed to the program. Success in a master's program may also demonstrate your ability to perform well in graduate-level coursework.
Request a meeting. Most academic programs have done away with personal interviews for admissions, but will usually entertain a meeting with an applicant if requested. Use that meeting to impress the faculty with your passion for the PhD program and strong research interests. Ask to meet with people with decision-making power that might be able to override the rules on GPA limits for special applicants. Set up a meeting with a department chairperson, a tenured professor or the director of admissions. Dress professionally, speak clearly and be honest about your academic pitfalls. Discuss how you would tackle advanced coursework and articulate your short- and long-term goals. Ask thoughtful questions that engage your interviewer.