Here's a clip from the review of an empty bay temp probe from Radio Shack. The choice words here are you get what you pay for. READ BEFORE YOU CONSIDER BUYING THIS THING!!!
"Made by Radio Shack the CP-VUE is basically LCD Temperature Readout stuck into a 5.25" computer cover. I saw this posted on HardOCP the other day and read it was only $10! I use the old Abit BH6 motherboard and it doesn't come with a thermal sensor that you can attach to stuff. Since I write reviews, overclock, and modify different types of cooling for my computer I need to know how hot my computer components are. This is where a Thermal probe comes in. There are other thermal sensor readout that cost as much as $50, now I didn't want to spend that much so I though this CP-VUE thing was a steal."
FULL STORY @ G3D (http://g3d.arashbest.com/temp.html)