Consuming a NAV 2013 Page using C# and ODATA : 

a very nice port about NAV 2013 OData Web Services

"As you may know, NAV 2013 allows you to access data in NAV via ODATA services as well as SOAP. While Daniel Rimmelzwaan put together a good overview of publishing ODATA in NAV (which you can read at NAV 2013 Beta - OData Introduction), I didn’t really see any tutorials on how to consume said ODATA once you’ve got it published, so after I spent some time figuring out how to make it happen, I wrote this blog entry.

Start by making sure you’ve got some NAV data published for access via ODATA. You can do this by pulling up the Web Services page in the NAV client, via Departments – Administration – IT Administration – General – Web Services. For this tutorial, we’ll be publishing page 21, the Customer Card, with a Service Name value of “CustomerCard”. Make sure you check the “Published” box, or the page won’t actually be available. "

.....

http://www.archerpoint.com/blog/Posts/consuming-nav-2013-page-using-c-and-odata

From Tom Hunt's blog on Archerpoint Blog