I make apps in my free time and I try to localize them myself, mostly using Google Translate, existing open source resource files etc.
Some words though, are very specific when it comes to computer or smart phone usage, so the translations I come up with can sometimes be totally out of context.
For example, how would you translate "tap", "long press", "swipe" and "flick"? These are typical words that come up all the time in smart phone usage.