I built a heatstick last week and love it. It's like a "love wand" for your mash (though it doesn't vibrate).
Anyone using coolers for mash/lauter/liquor tun might want to check this out. I'm now able to do step mashes and mash outs so much more easily, and I can bring my temps up a degree or two without having to add more water.
Making one is a piece of cake if you have any electrical experience. The only drawback is that really should have a dedicated line from your circuit box - as this thing can draw 12 amps or more.
Check out these links:
http://hbd.org/pcalinsk/HeatStk3.htm
http://www.cedarcreeknetworks.com/heatstick.htm


