Are there other counties that have their tax records on-line?

Yes, and here they are.

Alexander County, NC
Anson County, NC
Cabarrus County, NC
Catawba County, NC
Cleveland County, NC
Gaston County, NC
Iredell County, NC
Lancaster County, SC
Lincoln County, NC
Mecklenburg County, NC
Rowan County, NC
Stanly County, NC
Union County, NC
York County, SC