There were lots of suggestions on Jeremy Vine's show on Wednesday. Don't know if you can access it on the website. I have older children and they like the idea of a cold hot water bottle. Also draping a damp cloth like a muslin over a fan is supposed to work (damp not wet obviously).
we have a 'convair magicool' sort of air con unit - you fill the back with water, and the water basically cools the air as it is fanned - we leave this on all night, my ds is nearly 3, and we have had this for 2 years. It blows half into ds's room and half into ours iyswim, so not directly onto him. Our bedrooms are airless and there is no way we could sleep without this.
I have taken so long to do this, it will be snowing outside now - sorry