On the Christian Easter holiday, ham is the traditional centerpiece of the Easter Sunday dinner table. The reason behind this is simple.
Ham is pork, salted and cured. Back before the days of refrigeration, meat needed curing before storage. Pork was typically slaughtered in the fall and took until spring to fully cure. Thus, ham ended up being the main course for Easter dinners, a holiday that typically heralds the arrival of spring and general rebirth.
Many Christians fast during the time of Lent, many times forgoing meat. Easter marks the end of Lent -- another reason to celebrate by eating meat.