Google Short Links is a very useful link shortening tool, coming in especially handy when used to shorten links from Google Drive. Those that own a site and host it on Google Apps can easily add Short Links to their apps by installing it from the App marketplace. The link is here.
However, there are times when admins will forget how to log back into the Short Links controls. Most admins will set custom subdomains for Google Short Links, but the default is at links.domain.com, while the the default admin page is at links.domain.com/admin.py.
Simply pointing a browser at the links.domain.com URL may not always bring up the administration interface, so be sure to point it to the admin.py page.
Some more information can be had at Labnol.