Here is the response I got when I asked a priest about this:
priest said:
YOU WRITE: Are certain sexual acts between married people forbidden? What if one's spouse is not Orthodox, as is my case?
RESPONSE: In general, any sexual act that is "self-directed" -- that is, aimed at pleasing "me" rather than displaying my love for my partner -- is selfish and sinful. Also, any sexual act that is forced upon another person against his or her will would be considered sinful as well. Whether one's partner is Orthodox or not has nothing to do with this...
Please do not substitute any online advice for personal pastoral counseling. Sex is an important part of marriage. Even those Orthodox who decide to forgo relations in order to draw closer to God see it as an sacrafice (as in, an offering) to God not to be taken lightly.
Also, lets not forget that there is a very, um, well...hot love poem in the middle of the Old Testament that does not mention procreation at all:
Lover: How beautiful you are and how pleasing,
O love, with your delights!
Your stature is like that of the palm,
and your breasts like clusters of fruit.
I said, "I will climb the palm tree;
I will take hold of its fruit."
May your breasts be like the clusters of the vine,
the fragrance of your breath like apples,
and your mouth like the best wine.
Beloved: May the wine go straight to my lover,
flowing gently over lips and teeth.
I belong to my lover,
and his desire is for me...
Beloved: Awake, north wind,
and come, south wind!
Blow on my garden,
that its fragrance may spread abroad.
Let my lover come into his garden
and taste its choice fruits.
Lover: I have come into my garden, my sister, my bride;
I have gathered my myrrh with my spice.
I have eaten my honeycomb and my honey;
I have drunk my wine and my milk.
M.