Declt (pronounce dec'let) is a reference manual generator for Common Lisp. It extracts and formats documentation from ASDF systems, including the system itself, its local dependencies (subsystems), components, packages and an extensive list of definitions (variables, functions etc.). The formatted documentation comes with full indexing and cross-references.
Reference manuals are generated in Texinfo format which can subsequently be converted into info, HTML, DVI, PostScript or PDF.
Declt's homepage contains a lot of resources, including online documentation in various formats.