An account will give you two major advantages over the common rabble. One, it will let you reserve a name to post comments with. No longer will there be confusion as to whether a post was made by you, or if it's Levi pretending to be you. Secondly, a registered user can set site preferences, allowing you to turn off advertisements and choose a theme to display.
I will not use your email address for nefarious purposes. If you don't give a valid email address, you will not be able to uncover a forgotten password. Allowable characters in your username are the letters of the English alphabet, Roman numerals, a period, a space, a hyphen, and an underscore.