Others have already pointed out that this very forum's implemented in Arc, a Lisp dialect. Some large projects implemented in Lisp:

Operating systems

https://en.wikipedia.org/wiki/Genera_(operating_system)

Travel industry software

https://en.wikipedia.org/wiki/ITA_Software

Computer games

https://en.wikipedia.org/wiki/Game_Oriented_Assembly_Lisp

https://en.wikipedia.org/wiki/Crash_Bandicoot

Common sense reasoning

https://en.wikipedia.org/wiki/Cyc

and plenty more

http://franz.com/success/

I'm using Lisp to implement a visual dataflow programming language

http://web.onetel.com/~hibou/fmj/FMJ.html