Once. Had an app that was freaked that they were going to run out of numbers so we seeded them to max negative value so that they could increment all the way through that to the max positive value.
They didn't really need it, but it sure made them happy.
"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt
Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning