In the summer of Hippo, we managed to completely drain half a dozen whiteboard markers. Meetings alone wouldn't have accomplished this: it was the combined use through both meetings and random silly drawings that used them up. Now that the summer is over, I wish that it was possible to chart the time that the whiteboard markers spent between work and play, on the progress graph.
Prima facie it may seem like the amount of time spent coding and the quality of the code would be directly correlated. But I've found that one of the most important elements of effective team software development  is the time that the team spends together when work isn't on their minds.
I don't think that it's coincidence that we mentioned these extra activities several times during the post mortem. They're what make a team into a team. They build trust, confidence, communication, recognized specialization, and make a world of difference to morale.
Here are ways in which the Helium team was brought closer together:
- Common lunches 
- Goofing around on the whiteboard
- Maintaining enough confidence that we could joke about failure
- Hippo T-shirts
- Tuesday lunches
- Defiling the mascot
- Our very own coffee maker (mmmmm...)
- Trips to 7-11
- Penny tossing
- Office pranks
- Singing the same annoying songs over and over again 
- Playing our videogame of choice (You Don't Know Jack)
Each and every one of these activities contributed to making the team work. It will be interesting to see how the Pyre teams this term find their own ways to become a Real Team. My advice?  Find excuses to hang around each other after hours. Your code will benefit, the project will benefit, and -- most importantly -- you'll be happier while working on it, and maybe make some new good friends. We did.
 Slightly more important than even code comments. (But slightly less important than coffee.)
 Even when people brought lunches from home at the start of the summer, we tried to drag them along for anyway. Food consumption was the secondary activity at these lunches compared to an opportunity for conversation.
 HippoHippoHippo (to the tune of BadgerBadgerBadger), 'enry the 8th, I shot the sherif, etc.
 ...which I'm sure you were all holding your breath to hear ;-)