Adding butter (unsalted) or oil (olive or vegetable) in small quantities to bread results in a higher rise, a crisper crust, and a longer shelf life. When fat is added in large quantities, such as for brioche, it results in a softer texture and less volume.
Eggs. Eggs added to dough help with rising. A bread dough rich with egg will rise very high, because eggs are a leavening agent (think genoise or angel food cake). As well, the fats from the yolk help to tenderize the crumb and lighten the texture a bit.