Preheat oven to 400F. Arrange 16 silicone muffin liners on a baking sheet or oil a regular-sized muffin pan and a few extra muffin-sized ramekins. (Note: Fat-free muffins stick to paper liners so avoid them.)
Peel the peaches (if they are very ripe, the skin may easily peel off; if not, dip them in boiling water for 30 seconds and allow to cool before peeling) and remove the pit. Chop into 1/2-inch pieces. Mix with agave nectar (optional) and set aside.
In a medium mixing bowl, mix the ground flax seed with the warm water. Slit the vanilla bean open and scrape the seeds from the middle with the back of a knife. Whisk the seeds into the flax mixture and save the vanilla bean for another use. (Try storing it in sugar to make vanilla sugar.) Add the vanilla extract, lemon juice, and soymilk to the flax mixture and whisk well to combine.
In a large bowl, combine the flour, baking powder, baking soda, salt, and sugar or substitute. Mix well. Add the liquid ingredients and stir just until combined; batter will be thick. Fold in the peaches, making sure they are distributed throughout the batter. Fill each muffin cup to within 1/2-inch of the top. Smooth the top of each muffin and, if desired, sprinkle with chopped almonds. Bake until a toothpick comes out clean, about 15-20 minutes. Allow to cool before serving.
Nutritional data below includes almonds but not sugar. With sugar, 95 calories, 19.5g carbohydrates, 2.6g fiber.