Pinky: "Gee, Brain, what do you want to do tonight?"
The Brain: "The same thing we do every night, Pinky — try to take over the world!"

My memory is a bit fuzzy, but from what I remember, if the Brain had set his sights slightly lower, he definitely could have taken over a city, or perhaps a small state as the first step in one night, and left the rest of the world to following nights.

Along these lines, I was talking with Dan about why I thought of Stack Overflow/Exchange as being significantly more successful than Quora. I wouldn't be surprised to find out that they have comparable traffic, users, or other metrics. However, from an outsider's perspective, Stack Overflow made fast progress on its initial goal of being a good programming Q&A site. There was never a clear mission accomplished moment, but at this point its success does not feel in doubt. There were follow-on steps, some more successful than others, and a general upward-and-onward feeling.

On the other hand, Quora's goals from the start were outrageous (in a good way): “Imagine a world where I knew everything that I wanted to know, as long as someone else in the world knew it.” I'm sure that having J.J. Abrams give his thoughts on monster/action scenes is a milemarker on that path. However, it's harder to see how far they've come or to feel like the site has a well-functioning foundation/core functionality, since the path is a continuous curve rather than a step function.*

Google might be considered a counter-example to this; from very early on its goal was quite broad and audacious. However, having a steady stream of corpora to add shows definite progress. There is also the matter of perceived goals versus actual internal goals. Thefacebook was long discounted by some as being a site just for college kids, surely even after they set their sights higher. Having others underestimate your ambition (but not too much, lest they ignore you) seems beneficial.

In the end, this probably reflects my personal bias towards the incremental Ben and Jerry's model. Though less exciting, over time it can lead to pretty good results.

* All of this might be a reflection of my being more aware of what Stack Overflow has done over the years via their podcast; Quora is harder to keep up with.