Help! I am serving moussaka tonight to guests an would like to know what to serve as a side in addition to a green salad.

I agree with susan g, greek style green beans. Here's one from The Splendid Table and it's really good:
http://www.publicradio.org/columns/splendid-table/recipes/greek-style_green_beans.html

Something with green beans -- you can find Greek or Middle Eastern style recipes that are delicious.

Thank you. No potatoes in moussaka. Your suggestions sound good.

Does your moussaka have potatoes in it? If it does maybe a plate of roasted peppers dressed with oil, red wine vinegar, garlic and parsley might be nice. If no potatoes in your moussaka a simple rice or rice and orzo pilaf with some pine nuts thrown in is an option.