I know, I'm late to the game, but I'd like to say a few words about Bruce Eckel's "What is consulting?".
I agree with Bruce that there are pretty big differences between different types of activities that are often called "consulting". The differences are so big that it is not a good idea to use the same word for describing them.
Having said that, what I wanted to focus on here is how I think it can be a good thing to do lots of what perhaps isn't "real consulting" in order to be able to do some real consulting from time to time. For example, doing lots of development is one way of being able to give some reasonable advice about it.
It's not just one or the other. It's a combination. (As always?)