On your profile page under user tools you will see name history. I would love to change my username slightly but can't seem to find an option anywhere to. Thanks!
Click on your name at the top of the page > my settings > display name... Not sure if there's a post count requirement or not, but if there is, it's probably 100 posts... Just be sure of what you want, as you are limited in the number of times you can change your name within a year...