Due to the fast development speed of Ubercart, the translation of Keesje76 is currently outdated. I started from scratch, since I needed to maintain the seperate module translations files in order to keep up with the respective .pot files. This will make it easier to keep up with new Ubercart versions.
The translation is still far from complete, but I hope this is a good starting point (again).

README_NL.txt file content:

INTRODUCTION

This translation is far from complete. I think you can see this as some kind of 
guidance for further Dutch Ubercart translations. Please send your supplements/
corrections/comments/suggestions to remco@vioco.nl or post a message on the 
Ubercart forum (http://www.ubercart.org/forum/internationalization/389/dutch_translation...)

The translation is currently generated for Ubercart version beta1.

ENDUSER USAGE 

Unpack the nl.po.tar.gz file in a _temporary_ local directory. Use the nl_all.po
file to import the translations into your Drupal installation using the 
Localization module.


DEVELOPER USAGE

Unpack the nl.po.tar.gz file _in_ your ubercart module directory.
Use the module-specific translations (e.g. payment/uc_payment/po/nl.po) to edit
the translation. To update the all-in-one translation file, use the msgcat and 
msgattrib commands (see drupal documentation).


COMMON TRANSLATIONS

EN              NL
product         artikel
customer        klant
invoice         factuur
order           bestelling
account         account