If your eavestroughs are in the area of trees where leaves and pine needles can build up, the eavestroughs and downspouts can become clogged leading to the eavestroughs overflowing and causing ice-buildup and damming in the winter. A good way to prevent this is by having the eavestroughs cleaned and then leaf guards installed as shown in this picture. These will allow water to filter into the eavestroughs while keeping all the gunk out.

If ice-buildup occurs in the eavestroughs in the winter heating (de-icing) cables are a good solution as well.