A show of respect and remembrance, not worship.
We hold Japanese Buddhist memorial services for our deceased family members at out temple once every 7 days, for the first 7 weeks. Then we will hold annual memorial services for each deceased family member from there on out.
Also, I agree with the previous two posters to this tread. Although based on a Confucian form of ancestor worship, we view memorial services more as a show of respect and remembrance, not of worship. This process of memorial services assists the family members left behind to cope with loss. Ministers will typically offer sermons during these services that revolve around the Buddha窶冱 teachings of impermanence and interdependence.
Just to give you some idea what a Buddhist sermon for the dead might sound like, the following words of Rennyo Shonin are spoken at funeral services of the Jodo Shinshu tradition of Buddhism:
窶弩HITE ASHES窶
from Rennyo's Letters
translated by Hisao Inagaki et al
When I deeply contemplate the transient nature of human life, I realize that, from beginning to end, life is impermanent like an illusion. We have not yet heard of anyone who lived ten thousand years. How fleeting is a lifetime!
Who in this world today can maintain a human form for even a hundred years? There is no knowing whether I will die first or others, whether death will occur today or tomorrow. We depart one after another more quickly than the dewdrops on the roots or the tips of the blades of grasses. So it is said. Hence, we may have radiant faces in the morning, but by evening we may turn into white ashes.
Once the winds of impermanence have blown, our eyes are instantly closed and our breath stops forever. Then, our radiant face changes its color, and the attractive countenance like peach and plum blossoms is lost. Family and relatives will gather and grieve, but all to no avail?
Since there is nothing else that can be done, they carry the deceased out to the fields, and then what is left after the body has been cremated and has turned into the midnight smoke is just white ashes. Words fail to describe the sadness of it all.
Thus the ephemeral nature of human existence is such that death comes to young and old alike without discrimination. So we should all quickly take to heart the matter of the greatest importance of the afterlife, entrust ourselves deeply to Amida Buddha, and recite the nembutsu. Humbly and respectfully.
Respectfully, KZ