Shimenawa (七五三縄, literally "enclosing rope") are another common decoration during the Japanese New Year. Rice straw is braided together to form a rope, that is then ornamented with pine, fern fronds, more straw and mandarine oranges. They can represent a variety of auspicious items, such as the rising sun over Mt. Fuji or a crane. The shimenawa pictured above is the one hanging on my front door.
Used mostly for ritual purification in the Shintô religion, shimenawa can vary in diameter from a few centimetres to several metres, and are often seen festooned with shide paper. The space bound by shimenawa often indicates a sacred or pure space, such as that of a Shinto shrine.
Shimenawa are believed to act as a ward against evil spirits and are often set up at a ground-breaking ceremony before construction begins on a new building. They are often found at Shinto shrines, torii gates, and sacred landmarks.
They are also tied around objects capable of attracting spirits or inhabited by spirits, called yorishiro. These include trees, in which case the inhabiting spirits are called kodama, and cutting down these trees is thought to bring misfortune. In cases of stones, the stones are known as iwakura. (Adapted from the Wikipedia site.)
Most of the following photos were taken of shimenawa hanging at the entrance of restaurants in my neighborhood.