similar to the description, but gives a web page: https://github.com/mmontone/cl-livedocs with full-text search, and https://github.com/lokedhs/docbrowser
(also: slime-edit-definition, with a prefix argument, allows to go to the definition of any symbol)
nope these 2 links don't give the hyperspec, they build a web view of the systems, packages and symbols (classes macros functions etc) in the current image.