There are a number of possibilities. At Whole Foods, you should be able to find a product called Ener-G Egg Replacer (it's a powder, comes in a box, and it usually with the baking products). How well it works depends on the recipe--but it's usually best in recipes with fewer eggs. I've had mixed success--it will probably work better with a denser bread than with something light and fluffy (cupcakes, for instance). Ground flax seed often works really well (1 tbsp ground flax seed blended with 3 tbsp water). Sometimes a little mashed banana or applesauce can also work. You do really have to experiment to find what will work best with a particular recipe.
Personally (and this is not that helpful, I know), I find that recipes for baked goods that were vegan to begin with turn out better than recipes that are "doctored" to make them vegan. If you'd like to find an alternative, there are tons of free recipes at peta.org, vegfamily.com, vegsource.com (this board also has a recipe q and a section--if you'd like to post there, the chef is very good about getting back to you quickly about how to veganize a recipe), or you could just do a search for "vegan amaranth bread recipe" or something and see what you come up with.