I'm a fan of Adobe Lightroom. It has a great user interface - understated elegance and smooth user experience. And it does a great job, it's fast, and it's relatively small.
I knew Lightroom used Lua, for example in plugins. But I was surprised when I came across a presentation that said 63% of Lightroom specific code is written in Lua (with the remainder in C, Objective C, and C++).
That's impressive. Many people would assume that a program written in a "scripting" language would be slow and ugly. That might be true of many programs (scripting language or not!) but I think this proves otherwise.
I also find it reassuring because, in a sense, it validates the approach we took in writing our trucking software. We wrote it in Suneido (comparable to a scripting language) for many of the same reasons Adobe wrote Lightroom in Lua.
Of course, the difference is that they chose an existing language, whereas I wrote Suneido. I would not have been as impressed if Adobe had chosen to write their own scripting language. Of course, that raises the question whether we should have used an existing language to write our trucking software. If I was starting today, I might say yes, but given the situation when we started (years ago) I'm not sure I'd do it any differently.