Not only the way you speak—but the way you write and act. More than geography, accents now represent a choice of attitude.
Let's define an accent as the way someone speaks (writes, acts) that's different from the way I do it. So, if I'm from Liverpool and you're from Texas, you have an accent, I don't.
Occasionally, an accent is a marketing advantage. Sounding like Sean Connery might be seen as charming in a New York singles' bar, or sounding like a Harvard man might help a neurologist in Miami Beach. Generally, though, if I think you've got an accent, it's more difficult to trust you.
Can your writing have an accent? Of course it can. Not just grammar errors, but sentence length, exclamation marks and your vocabulary all tag you. And the fonts, colors, pictures and layouts you choose are part of your accent as well. Most of us have no trouble at all telling where an ad or a brochure came from (shyster, NY ad firm, home business, church flyer… you get the idea). This blog has an accent, but I've discovered that it's one that most of the people who read it can live with.
And your actions have a grammar as well. When your little mom-and-pop Middle Eastern restaurant has a policy (no substitutions!) even when the place is empty, you're speaking with an accent, aren't you? There's no right accent, no perfect set of rules or actions for you to follow. The choice of accent is directly related to the worldview of the people you're choosing to connect with.
Y'all come back soon, y'hear?