It ships the CD/DVD images with the full archive of this site and of its sister sites:
PDF of various size, plain and imposed, HTML, EPUB, TeX, source files are included.
Search plugin for [[http://calibre-ebook.com/][Calibre]]
Thanks to meskio, you can search and download the texts directly from Calibre.
See the Calibre store plugin wiki page for help.
You can download the plugin here: http://theanarchistlibrary.org/docs/theanarchistlibrary_store.zip (last updated August 24, 2012).
The code used to build, run and maintain the site is freely available. You can visit www.amusewiki.org to get it.
Documentation, credits, etc. is included.