When baking or cooking and in need of an egg, I use a mixture of ground flax and water as a substitute. This is not a novel idea; many packages of ground flax have directions to do it! There are a few ways to do it, but I have found the best way (and by I have found, I mean my mom showed me..hah!) to do it is like so:
Put 1 tbsp of flax and 3 tbsp of water into a small pot and bring it to a rolling boil. Let boil for 1-2 minutes, remove from heat and whisk vigorously for about 1 minute. The flax will become especially nasty and gunky sort of like snot. MMMMM! It will hang off your fork (or more high-tech whisking mechanism) in a particularly disgusting way, and you will know it is ready to be added to your muffins, veggie burgers, brownies, whatever.
One batch equals 1 egg substitution; if your recipe calls for two eggs, double the flax mixture, and so on..