thermometers

While at Aquamania, I heard a couple/few people talking about not having/using heaters on their aquariums (not sure if it was a Cichlid tank or not). I didn't get the opportunity to follow-up with them about not using heaters, but now I am more curious... Specifically, 1) Who has opted not...

What do you all think of digital thermometers vs. the glass one that go in the tank? Is there any specific brand that is more recommended than another? Thanks! -Rich