Like most I have frozen bottles of water and placed in sump with some success. Still those are some pretty hot temps.
We have gotten to over 37 degrees here in Whistler but my tank has not gone over 82 and I have no air conditioning. If it's any help I have been using the following:
2x Icecap variable speed fans (purchased at J&L like Wendel mentioned), they are unbelieveably quiet. I originally had one blowing in and one out but after the first day set them both up to blow cooler air into the canopy with venting from the back, this helped to the tune of 1 degree or so. I removed the plexi cover from the top of my tank so the fans are blowing more or less over the water, this has kept the tank below 80 degrees for the past two days. Lastly, I have a small clip on fan that blows directly onto the water of the sump. I have been able to keep the halides on for over 10hrs per day with no problems.
You can view the canopy I just built here:
http://reefcentral.com/forums/showth...hreadid=222009
Hope this helps,
Rob