Unfortunately Google has removed the "Ninja Dashboard" extension from the Chrome web store. The reason for the removal is that the extension doesn't have any real functionality, it just opens a web page, which is true.
As an alternative solution please use a direct link to launch the Dashboard:
- In the main menu select "Tools/Install Browser Buttons" to open the "Install Browser Buttons" page.
- Drag and drop the "Ninja Dashboard" button to the bookmark bar.
This button has been updated, too, from now it's a simple link to the Dashboard, it's not a bookmarklet anymore.
If you want you can also add the My Bookmarks page to the bookmark bar: open the My Bookmarks page in the browser then click on the star icon next to the browser's URL field and add the link to the bookmark bar.