what is it they say?... 'Red and green should never be seen'? seriously though re the comment about being opposites on the colour wheel. true, but the thing is when colours are like they they are referred to as being 'complimentary colours' and actually work quite well together.
I've got red and green highlights on my mainly grey and black Y33 and I quite like it. I also had a 'Palmer' metalic green Kona (not with any red) but it was very nice. (No photos of my bike unfortunately, but here is one from bikepedia.com to give you an idea of the colour.)