Not a Norwegian, but my wife and I honeymooned there in June. Some of the highlights:
* Rondane National Park. In the middle of the country, this is a massive park full of craggy mountains, crystalline streams, small farms. It's a countryside straight out of a fairytale. While we were there, morels were everywhere (a gourmet mushroom), and the cranberry season was just ending; other wild edibles might be in season when your friend visits. Absolutely spectacular. The hike we took through Rondane is possibly the most beautiful hike I've ever been on. Do not miss!
* Flam-Bergen Railway. I'll second Piratecat's suggestion: I had no idea so many gorgeous waterfalls could be in close proximity to one another.
* We didn't make it to Trondheim, but I heard good things about it.
* Bergen itself is a very cool city, nifty museums (the Leprosy Museum was, tragically, closed when we visited), and a great fish-market.
GENERAL TIPS:
It's a great place to go camping -- even though we somehow missed out on camping, we dragged our gear all over teh country side, and saw several opportunities for doing so. You're allowed to camp just about anywhere, due to ancient laws -- I think, as long as you stay a half-kilometer or so away from the nearest dwelling, it's legal for you to camp.
Rooms in private homes make a cheap alternative to hotels. Usually you can either get a breakfast they make for you in the morning (eggs, fish, cheese, cold cuts, coffee, etc.), or else you get access to a kitchen. If your friend can cook, the latter is great: it's very comforting to be able to make your own food when travelling.
Avoid Chinese food there! It's godawful nasty! Strangely, the Vietnamese food we tried was delicious, if a little weird. The only decent fish & chips we had was at the fish market in Bergen, and it was damned fine; other fish & chips would've put Mrs. Paul to shame. But the local fish was freakin yummy (although I never could develop a taste for pickled herring).
Is your friend going just to Norway? If they're going around Scandinavia, I'll mention that Copenhagen is a truly wonderful city, probably the finest city I've ever visited. In Norway, Oslo didn't really impress me much (although the park full of disturbing erotic statuary was pretty cool), and Bergen was worthwhile, but neither held a candle to the coolness of Copenhagen.
Finally
here's an old thread in which we solicited advice for our trip. Might be useful to your friend.
I hope they have a wonderful time!
Daniel