in fact, it sits in the Tools submenu
The Fiji Packager allows you to bundle an existing Fiji installation with all 3rd party plugins and added update sites into a single archive (.zip, .tar.gz, .tar.bz2 are supported at the moment).
After clicking on ''Plugins>
Utilities>Make Fiji Package'' (note: there are two ''Plugins>Utilities'' menus because ImageJ1 enforces separate submenus for non-core plugins which makes things a little bit confusing), you will be asked for the format and the file name.
After both are specified, the plugin does all the rest, reporting its progress in the status bar.