The straight-forward way to install libraries. Combine that with SBCL's (require 'system-name) and you are pretty much set.
Just (ql:quickload 'library-name).
- HTTP client: Drakma (one among many nice libraries by Edi Weitz)
- Regular expressions, other string manipulations: CL-PPCRE
- XML/HTML parsing: CXML-STP, PLEXIPPUS-XPATH, CLOSURE-HTML
And especially these two posts:
...and now I can close a few more tabs from my browser. Phew.