Can anyone recommend a good recipe for a frosting that isn't so sweet?  I need it to fill and cover the cake. I've always used buttercream but the client would like it less sweet and fresh cream isn't an option.  Help please! 

I highly recommend Jennifer Bratko's IMBC

http://www.cakecentral.com/recipe/26305/bratkos-strawberry-italian-meringue-buttercream-imbc

I love this recipe. not to sweet. You can use this recipe as a base and change up fresh fruit, or extracts to alter the flavor.