Update: Arbital Scrape V2
I've scraped http://arbital.com as the site is unusably slow and hard to search for me.
The scrape is locally browsable and plain HTML save for MathJax.
https://drive.google.com/open?id=1b7dKhOzfMpFwngAeI8efeOzv147Lv_mx
https://emma-borhanian.github.io/arbital-scrape/
If there's interest let me know as I may tidy up and open source my code. edit: working on this

Mirror: www.obormot.net/arbital
The scrape seems to be missing the Solomonoff induction dialogue, which was available at https://arbital.com/p/solomonoff_induction/?l=1hh (at the moment I just get an error).
ETA (2019-06-28): The new version of the scrape has this page, and can be viewed on the GreaterWrong version.