I guess the first question is "do you have a tagline?" I have one- "networker." That defines what I love to do, and hopefully adds value to those around me. But it is the tag that most people use who know me well, as well as those who are simply acquaintances.
Let me give a few other examples, strictly based on my opinion:
John Maxwell- leadership; 21 Laws
Don Miller- blue like jazz
Tony Morgan- strategic blogger
Darlene Zschech- Hillsong worship
Lanny Donoho- funny emcee
Beth Moore- women's bible studies
Rick Warren- Purpose Driven
Jeff Shinabarger- ideas
Mark Batterson- DC coffee shop
Marcus Buckingham- strengths
You may argue with some of the "tags" I've given to these folks, but the point is, whether you like it or not, you are being tagged. I believe "branding" and "tagging" are different. Branding is more about identity and emotion, where tagging is more about what I do. Sometimes they overlap, but most of the time they are closely associated but not necessarily the same. A tag is the subtitle of your book, if you were writing a biography. A tag is what comes to mind first when people think of you, that split second chance for someone to properly pull your file from their short or long term memory. A tag is no more than 10 words- a quick and concise snapshot of what someone sees you doing.
So are you creating your own tag, or is someone else creating it for you?