You're probably not going to get many useful answers, not because Lisp isn't widely used, but because nobody wants to reveal that they used Lisp, because:
- Lisp is their secret sauce, and they don't want their competitors to know about it
- Lisp programmers want to show off their app on its own merits, not because of the language used
- Non-Lispers recognize only that it's not a buzzword, and hence have no urge to mention it
- It's easy to hide it: web apps are really popular these days, and Lisp is great at web apps, but since it's all running on the server through a language-agnostic protocol, there's no way for users to tell that it's Lisp
- More generally, companies want to keep their cards close to their chest (independent of Lisp or even programming languages)
I know that part of every Amazon.com product page is generated using a Lisp service, but only because I had a beer with the guy who wrote and deployed it.
I wrote a web service that everybody who's seen loves, but mostly because it looks more impressive than it is. In fact, it happens to map onto Common Lisp constructs and free Lisp libraries almost perfectly, and is actually a fairly short program. If you take the curtain off something, everybody says "oh, is that all? I could have done that".
