Is it possible to add custom Dashlets to the main page of the Portal?

Hello,

When logging into the Portal in 10.0.1, we are presented with the Nav Bar, Search w/ Case Deflection, and 3 Dashlets: "All Open Cases", "Recently Resolved Cases", and "Knowledge Base Categories & Published Articles".

Is it possible to add a custom Dashlet to this screen?  Do they behave the same as standard Dashlets?

If not a custom dashlet, then is it possible to edit the Nav Bar as we would the standard Nav Bar? 

I'm looking to add hyperlinks to other resources outside Sugar Cases and KB.

Thank you,

Justin Kuehlthau