I work for Juniper Networks, where I get to use Lisp in a professional environment as a toolsmith. As of this writing, the deployed systems are based on CMUCL, which I really like using. However, I'm now moving to Xanalys LispWorks, because I need some of the libs that Xanalys has, and fast.
I used to be a volunteer sysadmin for GNU, but internal structure changes have ended that relationship. I am still a big fan of GNU and the free software philosophy.
I use GNU Emacs constantly.