Surveyors. That's the quick answer. Seems obvious and web searches will yield a plethora of sites that show trigonometry in surveying, but those surveyors have some deeper equations embedded into their programs. Mollweide's Formula is one of them. If you look at this equation, how many angles and how many sides of a given triangle are included in the formula? Why, from a number theory standpoint, would this be a good thing for surveyors -- what would they use it for? AND .....do you really think that the typical joe or jane surveyor would know this formula or even know of the existence of this formula?
Doctors. Particularly, radiologists use trig as they aim gamma rays into the bodies of their patients to eliminate tumors without traditional scalpels. How do you think trig is used in this area? Orthopedists use angles in their work, just check out the abstract to this article: http://www.ncbi.nlm.nih.gov/pubmed/7610093 or do a search -- there's lots available. Some images are not for those with a weak stomach.
Sailors. Just look for the triangles.
Rock Climbers and outdoor enthusiasts. Tyrolean Traverses (Can you find the triangles, angles to measure....?)
Astronomers....
You get the idea. In high school college-prep mathematics, trigonometry is often the first place students see direct applications of math in a variety of concrete areas. For your blog, find an application, a single application so you can develop it well, anything, and explain how trigonometry or the study of triangles applies to the field. Go ahead, ask parents, your friends' parents, anyone. Do they use trigonometry? Where? How? You might find lots of people who say, "Nope, never used it." Your mission is to find an application in the professional world.
