People have been appending ZIP archives to executables, in order to hold non-code resources, for time out of mind. The appendvfs extension makes the same thing possible for SQLite databases. An SQLite database has advantages over a ZIP archive in that SQLite supports a far richer data model, is far faster for random access, and has a query language. Both ZIP and SQLite are well-defined and very widely deployed formats. Many developers are more familiar with ZIP, but there are more than 1 trillion SQLite database files in circulation, and SQLite is a recommended storage format according to the US Library of Congress (https://www.sqlite.org/locrsf.html) so SQLite should not be dismissed as being too unfamiliar.
Example use cases:
(1) We have experimented with (but not published) putting all the SQLite documentation into an SQLite database and appending it to a special webserver app. Download the "EXE" and double-click on it and the SQLite docs automatically pop up in your web browser. This is better than a pile-of-HTML-files in that it can use server-side computing for things like the "Search".
(2) Not yet published or documented, but you can do "make sqltclsh" from the SQLite source tarball and generate a TCL interpreter with SQLite built in. If you also append an SQLite database to this interpreter, it reads its scripts from the database. Use this to build stand-alone Tcl/Tk/SQLite applications.
(3) By 3rd-party user request: the Fossil version control system allows a Fossil repository (which is just an SQLite database) to the end of the "fossil.exe" binary. This is being used (I am told) to provide a rich package of read-only but versioned content to non-technical users. The non-techies just put the "document.exe" file on there windows desktop and double-click, and a webserver pops up showing the reports they need, with complete historical versioning provided by Fossil.