There are many ways to re-purpose old frames. The ones with glass I use for my art but the bigger and more classic looking ones get a completely new life.
This is a small portrait I painted on a very old frame I found in the house where my grandmother grew up, in a remote village in Transylvania. The house was abandoned and literally crumbling down but I managed to retrieve a couple of old frames that were still hung. It turned out, unconsciously to look like my mother.
This one was made today by my husband as a display box for my wooden dolls collection.
Larger frames are even more useful because they can be turned into beautiful bookcases. My work-space is lined with such bookshelves, I find them more practical and aesthetic than the regular ones I had from Ikea.