When I talk to language-learning startups, I often ask them what their plans are for rolling out English-language versions. I see a lot of apps for learning to speak Spanish, French, Italian, and Chinese, but I think it's a missed opportunity to not create an app for learning to speak English. There's a huge demand globally for English skills, and I think that smart language companies recognize that.

In fact, I'm pretty sure when I met Jesse Maddox, the CEO of the Atlanta-based startup TripLingo, last month, I asked him just that: "where's the English version?" I've written a couple of stories about TripLingo's apps -- here and here -- and I like what the startup is doing in building apps that are targeted in helping you learn the phrases that tourists need, depending on your identity, your purposes for travelling, and so on.

TripLingo's just launched its latest app, and while hey, it's not an English-language one, I think it's one that does recognize untapped markets and that highlights the importance of having a mobile tool to help you master important phrases based on what you're doing abroad.

It's an app for learning Dari, the language spoken in Afghanistan.

"After talking to family that has served in Afghanistan (and an uncle that leaves for his third deployment Friday)," says Maddox, "I found out how poor/scarce current resources are for our troops. Since we've already put a ton of effort into our technology, we thought this was a great chance to use our tech and help out folks over there. We worked with a Special Forces translator with 26 years of Dari translation experience to update and fix the Defense Foreign Language Institute's Dari field guide, and then packaged it up in our app."

The Dari app includes 750 phrases with the Arabic script and with pronunciation help. There's also a searchable Dari - English dictionary, as well as a guide to cultural norms and etiquette. While the other TripLingo apps typically cost around $10, the startup is making this one free. Recognizing that not everyone has an iPhone either, the startup is also making all the contents of the app available as a downloadable PDF.