The best bong I have every smoked out of is a snow bong. Obviously, one can only manufacture this at certain times in the year, in only certain climates. (Unless one used crushed ice, which I haven't.)
Go out and buy yourself a nice 3' glass bong. (I realize that this might be out of the price range for most stoners.) Wait for the first snowfall of the year, and instead of water, pack the bong with snow about halfway up the tube. The snow cools the smoke and makes it incredibly easy to inhale.
The only other option besides snow that I have tried is using ice water in the chamber of the bong. However, unless one has a pretty large chamber on the bong, the smoke moves through the cold water too quickly.
HTH | 
