I agree that it's fun to experiment by adding things to the basic bread recipe, but you really need to understand what the outcome will be when doing so, lest the new baker become frustrated. Just adding things to the recipe, like an egg, will change the hydration (liquid content) of the dough by 2 oz. When you understand this, you'll know to reduce some other liquid by 2 oz., or you could end up with a very wet dough that you'll need to add more flour to in order to be able to knead it. You really need to approach experimentation armed with a bit of knowledge beforehand.
Baking needs to be more exacting than cooking to produce consistent results. This is why professional bakers and many hobby bakers use scales to weigh their ingredients, and often stay within certain percentages or ratios with their ingredients, based on the style of bread (stiff, standard, rustic) they are baking. None of this is difficult to learn, with all the information being online and in easily obtainable books, but when you learn these basic rules, it often takes the hobby baker to the next level, and makes the baking experience even more enjoyable. I have been doing this for about a year, and I continue to have "epiphanies" on a regular basis as I learn more about bread baking.
There are several good bread books available online, but I often recommend (because I own it) The Bread Baker's Apprentice by Peter Reinhart as an excellent source to get started with. You can get it at Amazon.com for $23.10 + shipping, and you will be amazed at how much information (including recipes) is in this one volume. There are others as well, and maybe Pie Susan or someone else can give a plug for some of the better ones from their libraries.
