There were some articles published about the NatTable. You can find them linked here.

• NatTable 2.2 - Verwendung und Anpassung des NatTable Widgets in wenigen Schritten (german)
• NatTable Advanced - Komfortfunktionen leicht gemacht, Excel kann das doch auch! (german)

If the direct links doesn't work you can find the articles and the source code of the associated examples here.