I love the idea of a producer in music as separate from an engineer - i.e. sat in the control room smoking a cigar shouting 'That's the single!' For many of us the dividing line is very blurred. Bands I work with want both engineering skills and production advice at the same time. I've recorded lots of stuff where my input has been requested and taken up. Admittedly, this is usually me saying 'I reckon it needs a synth there'. And I'm nearly there with the Rick Rubin beard...