I second "Ruby", but I'm deep in the web app development world. Despite the trend towards single page apps, there is still a large market for apps being develop

I second "Ruby", but I'm deep in the web app development world. Despite the trend towards single page apps, there is still a large market for apps being developed with Ruby-based APIs. Excellent Javascript skills are in high-demand, especially if you have a good understanding of one or more Javascript front-end frameworks.