Calculate Easter Sunday Date
SQL Server 2000: Tested
SQL Server 2005: Tested
SQL Server 2008: Tested
SQL Server 2008R2: Tested
SQL Server 2012: Not Tested
Date: Sometime over the last 2000 years
Most public holiday dates fall on dates/days that can be calculated with simple absolute (Valentines Day = 14 Feb) or offset (Victoria Day = 3rd Monday in May) rules.
Easter Sunday calculation follows a more complex set of rules called Computus, a definition of which can be found on Wikipedia.
The algorithm for calculating this has been ported through many systems, and the TSQL code below is a representation suitable for SQL Server.