Hot water circulator
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Today I stumbled on a website with a hot water circulation system that I had never heard of before, the Astro Express System, manufactured by Armstrong. It looks very similar to the Grundfos Comfort system. These systems are touted for solving your slow hot water problem.

This hot water circulating system places a typical recirculation pump such as those manufactured by Taco and Grunfos at the outlet of the water heater so that it pumps hot water out of the heater and into the hot water pipe.

Under each sink where you want "instant" hot water you place a special valve, the Astro Express Valve that connects between the hot water line and the cold water line. By hooking this valve between the hot and cold water lines you create a "loop" so the pump can pump water through the hot water piping to the valve, through the valve, into the cold water pipe, and back to the water heater inlet.

If none of the valves are open, then the pump does not pump any water, but when any of the valves open the hot water begins flowing through the loop sending hot water towards the fixture and the valve that is open. If more than one valve is open then hot water will flow towards both valves.