I rank BBEdit as one of those applications that few mortals ever get to make really hum. It has many features under the hood that go underutilized or completely forgotten. Take Control of BBEdit by Glenn Fleishman dives into this complex application.
Fleishman’s approach in the book is to take the reader through install, setup, and working with the various BBEdit features, working with documents, writing more efficiently with BBEdit’s tools, editing text, wrangling text (automating reusable text elements), search and replace, and then through working with web pages and sites. He does a great job of putting together how BBEdit users had to put together working with text, managing web sites, and managing projects to maximize BBEdit.