I was looking for a hazelnut filling for an anniversary cake and someone suggested just using Nutella, the hazelnut spread. Haven't tried it yet, but sounds wonderful!
I have made yellow cakes with a strawberry filling: mix together 8 ounces room temp. cream cheese, 1 to 11/2 cups cool whip or whipped cream. Fold in 1 pint of fresh strawberries, diced. Spread between cake layers. (Yields enough for one cake with two or three - depending on how thick it's spread - 9-inch cake layers.) Yummy and easy. Can also add honey or liquers to the mixture.