We ordered Stanley a cool bed to try and cool him off when it hit near 100 degrees in Seattle two week ago. (It's freezing now - highs in the 60s! yipes!)
I was a bit skeptical - they don't really tell you how it works and I had nightmares of it leaking all over. But, on the contrary, it's MAGIC! The bed is still cool 10 days after we filled, and you can see Stanley was happy to plant himself on it to stay cool! (you can see the ice water that was in front of the fan to his right..it was HOT).
They can be pricey, but we got a deal by buying it on ebay - definitely a worthwhile investment for a dog who won't get in the kiddy pool!