One of the challenges that attracted me to YouTube was the chance to grow the company from 100 to 1,000 people (not an actual goal but rather how i casually articulate our phase in-between start-up and large ongoing concern). At Second Life I got to help with going from 0 - 30 and at Google did the 1,000 to 10,000 order of magnitude experience). But this is my first 100 to 1,000.
In some ways it's familiar - you deal with many of the same recruiting, org structure and cultural issues - but I've become more cognizant of the LCD and his/her impact. The LCD is the "Lowest Common Denominator" -- basically the person who for a given quality or characteristic, demonstrates the most outlying behavior. This behavior can be a clearly negative trait (the person who works the least), outright positive or more ambiguous (the person who works every holiday). Either way, the LCD can have a very strong influence on an organization.
For example, the person who works every holiday could be a really dedicated passionate employee who models great behavior, but they also start to create a gentle pressure to work on off-days. The executive who seems to always be responding to emails at 3am is accelerating communications in a way that might also amp up stress and the desire to be "always-on."
There's a point where the Lowest Common Denominator" can start to shift behaviors - their actions become a meme which gets spread and imitated. One LCD who thinks it's okay to let deadlines slip - soon you've got anarchy. Ok, not exactly, but rather than anchor to the average person's behavior, the organization does start shifting towards the most extreme.
So what to do?
1) Be sensitive to outlier behavior which can be toxic and nip it quickly
2) If you want to change group dynamics, drop some positive LCDs into the system and see what happens
3) If you model LCD behaviors, be cognizant of its general effect on your team