Week 3 Theme

I'd like to have week three be a series of seven images with a common theme. Any suggestions?
Here's some from the Photography professor at Union, feel free to nominate one of these or one of your own:
->Paper bags
-Use a paper bag as the subject for each image.
->Half-/Century Club
-Photograph objects older than 50 or 100 years.
->Industry
-Images whose subjects are utilitarian or mechanical in design.

Feel free to use the comments section for ideas.
Enjoy the weekend!
~Danny