Stuart at Strange Magic has some interesting GM Merit Badges to help identify your GM style on web pages, Google+ notices, or perhaps even in flyers you might put up in your local FLGS. For future reference, I think this pretty much reflects my GMing style:I'm using a slight modification to Stuart's idea and indicating one minor element with a smaller icon. I definitely have a map that I work from, but improv is more important, and the map can expand during play as necessary. So, by adding a smaller icon for the Map merit badge, I'm telling people "expect this, but it's not a major thing."
There's a couple iffy parts. I wasn't sure if I should indicate Tactics with a small icon as well. It depends on whether you mean combat tactics specifically, or just planning in general.
I've proposed topic-specific badges as well, which I call "exceptions". For example, I could add a "Magic" line under my main merit badges and include the Tinker badge on that line. You could even have special icons for broad areas of the rules that would typically have exceptions. Here's my sample, with a different color scheme to distinguish it from the main icons.
I use different rules or a modified style for Magic in my games.
Follow this icon with one of the standard icons to indicate Gonzo Magic, Improvised Magic, Heavily By The Book Magic (material components strictly enforced.)
There could also be "genre" icons, in case you are advertising a game as a particular genre or mix of genres, or as a flavor tweak to otherwise standard pseudo-medieval fantasy. Again, in my sample, I came up with a distinct color scheme, to make it stand out. This sample icon doesn't apply to me, specifically, but it just happens to be the first one I did:
This particular game is (or my games typically are) in the Spy/Crime Genre.
Follow this icon with another genre icon (for a mix) or a smaller genre icon (for a hint,) or with other icons, like the Magic icon to indicate magical spies or criminals.
EDIT: corrected the time-stamp.