Have a field for Preferred name. Many peoplewant to be addressed by their middle name or nickname. But want to keep their first name in for formal documents. If there was a field called "preferred" name, that could be used for mail merges, exporting, etc. and still keep their formal first and nicknames in place.
As someone who goes by my middle name I understand this request. I don't consider this my nickname, in fact, I may have an entirely different nickname I also use.