It's also necessary for us to know a.) What platform (phone, Windows, Linux, Mac...) and/or b.) On the web or desktop? With the answer to these questions you s

It's also necessary for us to know a.) What platform (phone, Windows, Linux, Mac...) and/or b.) On the web or desktop? With the answer to these questions you should be able to easily find out for yourself what language to use, as it seems you have no preference. How fast you want the translations to happen matters because it will tell you how low level of a language you're going to want. If you're doing it on the web I would give PHP a shot as your main weapon, with the regular open web technologies for client side (JavaScript, HTML, CSS... just building the page). If you're going for a Windows desktop application, I would use C# because I consider it relatively easy to get into and will probably be powerful enough. Some extra programming 'oomph' is going to be put in to get into lower languages for better performance. If you're going for the phone you have to think about what kind of phone. If you want the application to be accessed through the web, then well, there's your answer :). For the Windows Phone 7 you can use C# with Silverlight and/or XNA to create your translation application. So, with C# you can create a C# desktop app and port a -lite version to the Windows Phone 7 with little hassle ;).