SLIME, the Superior Lisp Interaction Mode for Emacs
If you're doing serious Common Lisp development you should have a look at the complementary SLIME, which gives you the ability to develop Lisp programs interactively.
Portacle, a portable and multiplatform development environment
See Portacle, the portable and multiplatform development environment for Common Lisp. It's the easiest way to get SBCL + Emacs + Slime + Quicklisp + Git.
- lisp-lang.org (presentation, success stories, modern tutorials, wiki, recommended libraries)
- reddit/r/common_lisp (see its links)