Bulbs Unlimited sells a kit for making light fixtures out of spent bulbs. While we try to avoid buying an extra thing to make use out of old things, we enjoyed the gallery of the resulting projects.
The kit revolves around a device called the Inkubator, and includes snap buttons, glue, a socket, hanger and instruction manual.
The Inkubator is a holder for the spent bulbs, with numbered guide holes in it for marking the bulb where the glue for the snaps will go, corresponding to patterns in the manual.
You also have the option of buying the finished fixture, and circumventing the whole make-it-yourself aspect. The components of the kit are also available for purchase individually.
Learn all about it here.