@ PaulS: I am relatively new to Arduino so didn't really understand what your code is doing there, had a look on the Arduino site but they don't give much explanation on highByte and lowByte...would you mind elaborating. I copied your code in but retrieved on the serial for case b on the slave: 200, 1, 44? Do I need to do something to the slave code? I imagine something must happen to the 'receiveEvent' function, but still how I see this function to operate is I must have the same Wire.read()'s as the amount of data I'm sending? Implementing your code means I have to have a different amount for Case 2 than for Case 1 and 3 in the master. Do you see what I'm saying?
@Constantin: Thanks very much for that bit of info, had a brief look at it and will give it a go!
One last thing, I will be operating 3 x ATMegas standalone, one master with two slaves. I have wired them on a breadboard as shown here: http://arduino.cc/en/Main/Standalone. This may not be the right place for this question, let me know and I'll move it if so but does anyone know if I can run all three off the same crystal? At the moment they each have their own with 22pF caps. Also is there any risk of things running out of sync?
Many thanks