Although not an air conditioner (and not sure whether it would easily fit into your window), but I have something similar to this:
http://www.canadiantire.ca/AST/browse/3/HouseHome/1/HeatingAirConditioning/ElectricFans/PRD~0435611P/NOMA%2525AE%252BDual%252BWindow%252BFan.jsp?locale =en
It works surprisingly well, especially if you set it to "exhaust" so it sucks the air out of the house. Seems counter intuitive, but it cools the house much better. Our bedroom is at the back of the house where I leave the window open a bit, and I have this at the front spinning away all night. It creates a nice through draft and makes the house noticeably cooler.