I see my specialty as being a bridge between techs and "the rest of us". While even the mention of technical writing may induce yawns, it's a skill that can be critical to the success of a project, and it's something that I do very well. The more concrete one can be in describing a project, the better chances that it has in reaching goals, meeting client needs, avoiding unrealistic expectations, and so on. Also, while one would never directly use the material for marketing and sales, it still often proves useful to compare "this is what we tell people we do" to "this is what we actually do".
That skill, in turn, has led to several hundred successful small outsourcing projects, (emphasis on the word "small", as that's part of the key to success). I'm both a client and a worker on Upwork, and on vWorker prior to that. The ability to define things in excruciating detail excites those who know how to actually get things done, and scares those who don't.
While it makes sense that database design is done by techies, the better that a project is defined from "the rest of us", the higher the chances are that the database will be designed correctly up front. This, in turn, has a significant impact on how quickly software can be delivered. Conversely, there are too many times when the techies find out "oh, I didn't know that you really meant that" way too late in a project for something that was designed and built into the fabric at its very beginning. Think of it as making sure that you pour the correct and sufficiently robust foundation for your dream house before you build the rest of it.
Yeah, I also do PHP and MySQL, but it sounds like there are already enough techs here in the soup.
I've also learned a lot about voice acting over the last two years, and I can also do reasonably well when it comes to basic video editing. Tie those together along with my tech writing skills, and I can create some killer educational and sales videos. Here's my current demo reel: