1. Being used to successfully produce "waste" domestic hot water. There are 2 main types: desuperheaters and dedicated heaters. In cooling dominated areas, a dedicated heat pump water heater dehumidifies indoor air quite well. Desuperheaters are built into the outdoor unit, and plumbed to whatever heat store they serve. They work better in cooling season than heating season, due to the higher ambient condensing temperature.
2. Many window and through-wall air conditioners use this principle to improve efficiency. The cold indoor evaporator pulls moisture from indoors and deposits it in a drain pan. This drain pan leads to the outdoor fan, which has a ring around its circumference. When sufficient water has accumulated in the drain pan, the outdoor fan slings the water onto the condensing coil as it spins. The direct contact and evaporation keeps condensing temperatures a lot lower than they would be without it. Needless to say, this method works better on humid days than dry ones.
Another super-effective idea to employ to reduce indoor humidity is the "desiccant waterfall". It works much like a swamp cooler in reverse. Salt water is circulated indoors and grabs moisture from the air. This solution is pumped onto a hot solar collector, and the water evaporates. The salt water circulates back indoors to suck more water from the air. I know you're thinking "What about that solar heat? Won't it warm my house?" The answer is not if you don't pump too much water. Remember, a couple of gallons per hour is all that can be wringed from the air in your home.
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