As a swimming pool owner, I am constantly looking for cheap, efficient, and viable ways to increase the temperature.  I'm not interested in buying a gas heater as the cost would get a little out of control.  I did however build a solar heater out of 1/2" irrigation hose.  I'll save that story for another time. 

Now that pool season is upon us, I started to look at new options for heating the pool, or ways that I could improve my existing build.  When I came across this site, I almost died laughing.  I think it's feasible, but wow.  Just wow.  You have to see it to believe it.

Check out the Redneck Pool Heater