The ability to write functional computer code, for one, which is a superpower.

Besides that, I speak the language, engineering folks generally like working with me over working with "icky marketing types", I have a good understanding of what is easy and what isn't in terms of implementation, I can spec projects or deliver prototypes without needing my hands held too much, etc etc. (And virtually my entire shtick is "Marketing objectives which are worth serious money to you can be achieved by writing carefully considered code.")

But in terms of writing functional computer code...how much are you actually writing? Is this code merely to wireframe/prototype something? Or is it an actually deliverable that the company will build atop?

I guess what I'm getting at is the usual cynical trope by engineers against consulting: that consultants are hired to tell you what you already know/should've known. So given a hypothetical company of such stature as Fog Creek, what is your strategy for convincing them that you can tell them something they don't know? I'm not saying that engineers are above needing consultants, it just seems like a culture that, as you point out, can be extra-resistant to being told by a third-party what to do, in lieu of a concrete deliverable.

Depends on the engagement. There is code I wrote running in production at some clients. (Might want to keep an eye on the FC blog, as I expect there will be something interesting on there eventually, but until then that isn't my story to tell.)

So given a hypothetical company... what is your strategy for convincing them that you can tell them something they don't know?

I tell them something they don't know, and continue doing so until I win the engagement.

With specific reference to Fog Creek, I was active on their forums for a few years and folks there read my blog, so I wasn't exactly starting from a position of We Totally Don't Know Anything About You on the credibility ladder.

Quite frankly, most people have no idea what's possible with programming. I once worked at a company where they spent dozens of hours each month manually updating monthly reports in Excel spreadsheets. If you watch the average person work, you'll see dozens of things that could easily be automated or simplified. Watch a little more, and you'll see the possibility to add new capabilities that simply weren't possible before.

Simple, reduced risk. Patio11 has built his personal brand very successfully. (not overnight mind you) So much so, that you know exactly what you expect to be delivered when you would engage with him. Much of the content that he produces (especially that which is consumable by you and I) gives a very good indication what you would expect if you worked with him.