Have any of you devised an easy way of keeping fermenters warm during the winter months? I know there's bucket/carboy heating pads and the like, but I was wondering what other methods have been successful for you all. I'm wanting to brew a Hefeweizen next month and keep it above 70° to accentuate the banana and clove esters. Here in Michigan, it's tough to keep my house above 67° or so without the furnace continuously running. Space heater in a small room? I'm know the easy answer is just "wait until Summer", but this brew is a gift for someone's birthday in mid-February.
What's worked for you?