The Insight Works Universal XMLport allows you to quickly import tab-delimited text files into any NAV 2013 table without any development or configuration.
Much faster than pasting from Excel or using the data migration tools.
Update 5/02/2014:
Latest update allows you to import Record Notes and Record Links. See documentation header in code or forum for how to import notes/links.
Works with 2013 and 2013R2
Update 5/07/2013:
Adds ability to import item tracking lines (serial/lot numbers) on the item journal and reintroduces the ability to run triggers.
To import serial/lot numbers, include the serial no. and/or lot no., expiration date, or warranty date in the import for table 83 (Item Journal Line). The XMLPort will create appropriate item tracking lines based on that data.
Update 5/06/2013:
Newer builds of 2013 enforce the MinOccurs property. This update to the XMLPort addresses that issue.
Update 17/10/2012:
Adds ability to run OnInsert and OnModify triggers and fixes an issue with xRec being equal to Rec when validating values