I love my Maverick Wireless Temp Probes.
http://www.maverickhousewares.com/et7.htm
They can be purchased for much less than the home site. Amazon etc.
I use them every time I use the smoker. One to monitor the cabinet temp and one for the internal temp of what I am cooking (pork shoulder etc.)
I can have the receiving unit inside, on my kitchen table or on my nightstand for those all night smoking sessions.
You can program in an alarm to go off when it reaches a certain temp. Very handy.
I used it in the thigh of my 20 lb turkey this year for a perfectly cooked bird.
Highly recommended for pro and novices alike.