Good libraries for PID control systems

I'm currently working on a temperaute control system based on a PID controller. I am familiar with the standard Arduino PID library and I'm wondering, if there are any other good libraries for PID controllers, especially for temperature control.

The basic PID calculation is about 5 lines of code, so you don't need a library.

The difficult part is finding the proper coefficients, which has nothing to do with the code.

jremington:
The basic PID calculation is about 5 lines of code, so you don't need a library.

Having said that, the Arduino PID library does resolve a number of issues with just doing the simple calc. Explored here: improving the beginners pid

I have not started doing real stuff with Arduino PID library yet:
I really like the 9 part blog series wildbill pointed to.

Not sure whether manual tuning will be needed for my scenarious, but Wikipedia talks about that:

Hermann.