Olga,
Helga,
Inga and
Ingrid won't be most people's cup of tea, I suspect. They are too "heavy" sounding for popular tastes. But that's what I love about them. They are a refreshing change form the usual kind of name.
Olga Lavinia is Appalachian_Pie's combo and it still strikes me as very pretty and old world charm-y.
Helga has the most "ugly duckling" quotient and needs to be handled carefully. I can see a
Helga Marion or a
Helga Lenore -- nothing too frilly.
Inga is so sweet. It's very musical sounding to my ears.
Ingrid is the most accessible for the general public. I once used the combination
Ingrid Maia as a pseudonym on another site. I still think it's pretty.