I like the idea, I bought it and have it open all the time, however I don't find myself using it that often. That's probably because I know most of the tools I work with out of memory (angularJS), and the documentation I do have to look up sometimes (UnderscoreJS) I actually prefer to see in the browser; the navigation on the browser version has a better subdivision in Underscore modules (functions, arrays, objects etc) which Dash's index is missing.

(subtle feature request: subcategories for the underscore docset, or headers/sections in the method listing)