if you rent bikes, do it at the camp grounds - they don't have a two hour minimum. In one hour we could ride out the end of the bike path and back to the waterfall. Outside of Flam, the fjords are incredible.
Homenkollen Ski jump is worth the trip. Easy tram trip and 10 minute walk. Ski enthusiasts will love the museum and those who remember Wide World of Sports and the thrill of victory and agony of defeat will really appreciate being able to go to the top of the jump. Frog... park is beautiful. Naked people statues are a trip.