The FileHelpers are a free and easy to use .NET library to import/export data from fixed length or delimited records in files, strings or streams.
The idea is pretty simple:
You can strong type your flat file (fixed or delimited) simply describing a class that maps to each record and later read/write your file as an strong typed .NET array
The Library also has support for import/export data from differents storages like Excel, Access, SqlServer, etc.
The FileHelpers are completely free because they are released under the LPGL Licence that allows the use of the code and binaries in all places, also in commercial applications.