The long stem round dial temp gauge works well. I use the one I got with my turkey fryer. As Barbarian points out, it tells you what the temp is down in the middle of the drum. I find that I'm consistantly showing about 40-50F higher temp down in the drum than what my gauge shows on the lid. Between the two of them, I get a really good idea of what's going on, and adjust accordingly.
-=- Jerry -=-