Shooting a series on one subject always feels like a great exercise to me. Not that it just builds a visual muscle, but it can become a very natural part of your day and help you continually look at a subject many different ways. And discover something new along the road. Now you don’t think that Edward Weston only shot ONE pepper do you? I think his most famous is #33.
Personally I have been shooting lunches for over 17 years.

Here is a pretty cool series from Jon Huck: Breakfast
[photopress:david_cowan_2_3L.jpg,full,centered] .Check out his site for some more work. And you can purchase his books through the BLURB.COM bookstore.

The point is, your development as a visual artist can be aided by a constant exploration. Sometimes it’s the familiar that serves as the perfect subject. A daily routine, a regular activity, or perhaps someone you see all the time. Photography becomes a perfect medium to interpret the passage of time, or the similarities throughout a common thread of a subject.

Another good reason for having your camera with you at all times.