SmartXLS is a high performance .NET Excel component
which can write, read, calculate Excel compatible files
without the need for Microsoft Excel on either the developer or client machines.
It was entirely written in 100% managed C# code.

Cell formatting
formula calculation
read/write Encrypted Excel files(xls and xlsx files).
create Chart,pivot table from scratch
export/import data to/from datatable

New release features:
Excel2007 tables support.
Excel2007 ConditionFormat support.