Software to check out

Editors

• Emacs, of course. I am a Lisp programmer, after all.
• Neovim. Vi improved improved.
• Kakoune. Vim on steroids.

Window Management

• dwm, the vim of window managers.
• StumpWm, the Emacs of window managers. Written completely in Common Lisp.

Operating Systems

• Artix Linux. Like Arch Linux, but without systemd.
• Mezzano. A modern Lisp operating system.
• GNU Guix Linux. A scheme machine with Linux Kernel. And you can run it on the hurd kernel!

Others

• Emacs Org Mode. It's just perfect for about everything.
• Glamorous Toolkit. A Programming Environment implemented on top of Pharo Smalltalk.
• Unix userland. Seriously, everytime I am on Windows I miss this stuff. Yeah, I know I can get it there as well, but it's not the same. And the BSD folks are right: it is more coherent over there.
• Man Pages.