If you are planning on doing some sightseeing in Oslo, I recommend you buy the Oslo Card. The price is not bad at all (surprisingly), and public transport (ferries, buses, trains, trams; that alone costs over 60 NOK - $10 - for 24 hours) is included, as well as the entrance fees to all the major sights and museums. If you're only going to 2-3 museums and will be using public transport for more than 3 trips, you get good value for money. See VisitOslo.com  for more info on all sights and activities in Oslo and how to get there. Also check out the travel planner in Oslo, trafikanten.no (click on the British flag on the bottom left side of the page for information in English), which helps you find the right bus/tram/ferry to where you want to go.

Munch museum E-mail

The famous "Scream" can be wieved at the Munch Museum. This masterpiece (together with the Madonna), painted by one of Norway's most famous artists received a huge PR boost when they were stolen in 2004. Recovered in 2006 after one of the biggest bank robberies in Norwegian history, they have unfortunately been damaged for ever, but have been restored and are back on display.

 
Are you spending summer in Oslo?
 
Have you tried the Oslo Pass yet?