Triggers have uses, but I'm not sure that business logic is a good one.
For me, auditing is the main use. In 2008 Change data capture and change data tracking can also be used for that, but not everyone is using 2008.
Other thing that they can be used for (especially the DDL triggers) is rolling back unauthorised changes, though if you have that kind of changes been made either security is lax or the DBA is careless.
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