Here are some I like, that are maybe a the more original side:
Océane / Océanne (was very popular in Québec in the 2000s. It's not pronounced like the word
Ocean, more like Oh-SAY-ANNE. Rhymes with
Anne.)
OdileOlivine (like the gemstone, but was also used as a diminutive for
Olive)
OlympeOksana (though not in my culture, I think it sounds so beautiful)
OrianaOrianeOrla
If you want really original there are these choices:
Ondine (from the Latin for ''wave'')
Orchidée (I've seen it online but not in real life. It's French for ''orchid'')
Don't hesitate to rate my different PNLs:
http://www.behindthename.com/pnl/246179