2. Stretching & Flexibility: How to work with your Stretch reflex...David Holt
Allow the heel to drop down slowly until resistance is felt in the muscle or tendon, hold for the usual length of time before pushing up (which is, of course, exercise) Do some stretches with straight knees to stretch the gastrocnemius muscle, do...
http://home.sprynet.com/~holtrun/stretch.htm

3. Ask an Expert: Remedies for chronic plantar fasciaitis -- Netwellness Homepage
Stretch the calf with the knee bent and with the knee straight. Stretching should never be hurtful, so stretch till you feel a gentle stretch. Stretching should be held 10-15 seconds and repeat each stretch 3-5 times to begin your routine.
http://netwellness.org/question.cfm/9327.htm

4. Comfort Measures during pregnancy
In order to stretch the calf muscle keep your knee straight, your ankle bent, and your heel on the floor. Gently pull your knees toward your shoulders until you feel a slight stretch in the lower part of your back.
http://society.indianetzone.com/pregnancy/1/comfort_measures.htm