Polder Original Cooking All-In-One Timer/Thermometer
Recommended by Alton Brown, this thermometer allows you to set the desired final cooking temperature or a timer.
Taylor Elite Instant Read Dial Thermometer
A reliable and inexpensive tool, you can simply insert this to find the temperature. The main drawback is that you will have to open the oven door to insert it and check which means losing heat.
Steak Station Digital Meat Thermometer
On the higher end of the market, this nifty tool lets you measure the internal cooking temperature of up to four steaks at the same time.
ThermaWorks Super-Fast Thermapen Review
On Steven Raichlen's grilling wishlist, this is a top-of-the line instand-read thermometer. The only down side is the cost, but you have to think that these are quite durable so you won't waste money replacing cheaper ones.