Read the Manual (or a photography book) – Each day, read a section of the camera manual or a photography book. Take several pictures to experiment with the settings or techniques described. Select your favorite photo from the set as the photo for the day.

If necessary, a section may be split over several days. Repeat settings or techniques each time they are discussed in a new section. If no particular setting is described, take a "creative" day, where you shoot a subject you haven't shot before, or haven't shot in a while, using previously learned settings.

Word of the Day – Attempt to take a picture to express the word of the day, such as from a dictionary site. You can also use cards from social word games, such as Taboo and Pictionary.

Guessing Game – Each day, multiple people take multiple pictures based on abstract themes on random cards from a social game. Periodically get together to guess and discuss the themes of each others photos.

Timelapse – Take a picture of a given scene at a set time each day. Try to pick a scene that will change with the seasons and holidays. Assemble into a time lapse at the end of the year.

Self-Portraits – Similar to the time lapse, except with self portraits. You can see how you've changed during the year.

Broken Camera Challenge (per Hueco) – Get an 8-sided die and a 20-sided die and correlate your aperture and shutter speeds to each number. Now roll. Those are the settings you now have to use.

Traveling Gnome – Kidnap your father's garden gnome. Mail pictures of the gnome posing with various landmarks around the world to your father (a la Amélie).