OK. So here's a frustrating scenario. You have a document library with a required column on it. One of your users is about to leave for vacation and uploads some documents to the library. She is in a rush and forgets to enter the required metadata. The documents remain checked out to her.
Unfortunately, no one else can see the documents because they have never been checked in. Even the site owner can't see the documents.
Fortunately, there is an easy way to handle this situation. The site owner can go to the Document Library Settings page and click on the link to Manage checked out files.
From here, he can select the documents and click the Take Ownership of Selection link.
Now, the site owner can enter the missing metadata and check the documents in so others can see them.