plz provide a link.
I use an infra-red temp gun. Kinda like this one, but not this model (I just picked a random one off of google):
The less expensive ones aren't as accurate, but they're super convenient. I use them to check fishtanks, when cooking, and of course to play with the cat using the laser pointer.
I've found the stick-on ones to be very unreliable. I just peeled mine off and threw it away the other day.
I use a digital thermometer.. bought from Ebay, works great and uber cheap =]
I have a digital heater that has a built in thermometer