Some more things to enjoy in Oslo:
- The museums of the Bogdoy peninsula: take a ferry from the terminal in front of the Radhus, and go see the Viking ship museum and the Fram museum. Fram is the ship used in Acrtic explorations by Nansen and Amundsen. (Bogdoy should have those 'o's with the stroke through them, but I don't know how to do that here.)
- Vigelandsparken -- a sculpture park just out of town (tram number 15). This is a collection of sculptures by Norway's most famous sculptor, and well worth the trek. And you get a nice walk in the park too. And did I mention it was free?
Also, you can see The Scream at the Munch museum. There are actually a lot of versions of this, and I think this one is better than the one at the National gallery.
Also, enjoy an evening stroll in the gardens down Karl Johans gate -- but take a small handgun for the inevitable piano-accordianists!
Also, .... um ... no, that's about it really. Oh, there's a supermarket on Grensen (and elsewhere) where you can buy food for a picnic. The restaurants will kill you (or at least your wallet). Actually, two I found that were OK were Mona Lisa on Grensen (your basic Italian food), and Sjakk Matt on Hakon VII's gate (also Italian, but more hip).