Gender neutral names are actually really uncommon in Norwegian. Neutral forms of names that have female and male versions are also very uncommon. Male and female forms are common, though. I'm only listing names that I think have a scandinavian or germanic origin.

Audun - Audhild
Tor - Torild/Torhild
Ragnar - Ragnhild
Erik - Erika
Ulf - Ylva

Yes, the -hild suffix is a common way (although trending downwards in popularity) to give a feminine form for names in norwegian, but it can't be carelessly attached to any masculine name.

It is a lot more common for male names to have female forms, than it is for female names to have male forms over here. This makes it a bit hard to make a substantial list.