I decided to dabble into custom fields. I have scripts to add, remove, rename and set custom fields. I also have a cool script to export your custom fields to a CSV file and vice versa.

Prerequisites:
VI 3.5 (VI API 2.5.0)
Latest VI Perl Toolkit (VMware VI Remote CLI will install this)
Text::CSV_XS (Perl module for CSVs)
Text::CSV::Simple (Perl module for CSVs)

Scripts:
addvifield.pl - Adds Custom Field to VI
cf2csv.pl - Exports Custom Fields to CSV File
csv2cf.pl - Imports CSV File to Custom Fields (Note: Custom Fields must already be created)
readdcfields.pl - Reads all Custom Fields from every VM in a datacenter
readvmfield.pl - Reads a single Custom Fields from a VM
readvmfields.pl - Reads all Custom Fields from a VM
removevifield.pl - Removes a Custom Fields from VI
renamevifield.pl - Renames a Custom Field in VI
setvmfield.pl - Assigns a value to a Custom Field in a VM
setdctools.pl - Reads VMWare Tools Version From Each VM In A Datacenter And Applies It To The Custom Field "Tools Version"