Lifted wholly from 37signals' SvN blog:
Slack All the stuff that doesn’t fit neatly into bigger, concept-driven iterations. We save one of our programmer/designer teams for slack work — small scope things that build up, a bug that needs to be fixed, a quick support assist, etc.
YAGNI You ain’t gonna need it. It’s easy to get carried away discussing how you could possibly do this, that, or the other thing. It’s harder to step back and ask “Are we really gonna need this?” The answer is usually no.
Low ceremony When it comes to workflow or policies, stay away from posturing. Just stick loosely to a few guidelines and let good judgement lead you the rest of the way.