(require srfi/n)to load up the nth SRFI; they're numbered. Particularly, I've been playing with the extended libraries for lists, strings, and hash tables.
On the Common Lisp side of things; I just ran across the insanely useful
describe, which prints out what the system knows about a given object -- if it's a function with a docstring, the docstring will be in there. Also potentially useful:
disassemble. Give it a function; it does what it sounds like!