I'd be surprised if places with active geothermal vents would even notice the human induced heating. In that case Iceland seems like an excellent choice. The main problem is when it comes to active fisheries being located near the effluence.
Another thing you can do is to simply use the slightly warmer water like you would use cold water. Half of downtown Toronto's office towers (including 151 Front) are cooled with water from Lake Ontario that then enters the city's water supply.
Just as Cornell U uses the water from Cayuga Lake. Pretty cool :)