Anarki: a publicly modifiable fork of PG's and RTM's Arc Lisp (http://www.paulgraham.com/arc.html)
To run, install Racket from http://racket-lang.org, then run arc.sh. To quit: arc> :a $
If you run into trouble: http://sites.google.com/site/arclanguagewiki
To run the HN server: lib/how-to-run-news