Which filters are the most commonly used and easier to implement for ECG noise removal? ECG signal is affected by interferences such as the Powerline Interference, Baseline Wandering and Muscle Noise.

There are many filters available which can reasonably cancel these types of noise.

I've found that Butterworth, Chebyshev, Wiener and Kaiser filters, along with wavelets could be used for this purpose.

Now, my main questions are:


Which filters are the most commonly used and easier to implement
(both from the above list and from other filters you have in mind)? 
Can you provide me some pseudo-code samples on how to implement some simple filters, maybe Butterworth or Wiener?
In which references should I look at concerning ECG digital
filtering, I mean which provide an overview of the various filters instead of foccusing on a specific one?


Thanks in advance
Different filters are used for different purposes. Removing powerline noise, which usually is concentrated at a single frequency, is usually performed with a notch filter. Removing baseline wandering is usually done with a DC blocking filter, which is a very narrow high pass filter, and is essentially another notch filter with 0 Hz center frequency. Removing EMG is usually more difficult, but you can try doing it with a low pass filter, since EMG has a lot of content in high frequencies.

In order to process EEG signals for simple things like heartbeat rate detection, look at the Pan-Tompkinks algorithm. 

Questions 2 and 3 require some effort on your part, since they're very broad. I've used this book in a graduate class on the topic, and I found it to be very insightful.