As part of the work I was doing with White October in Oxford, I was asked to work on the Said Business School site with some of the team. The task was to improve the homepage by making it much more modular, using views and panels so that it was easy to manage.
The hardest part of this was documentation of how content insertion would need to change, and also allowing us to still cater for extreme cases (so nodequeue was used to force promote and order items).
Another part of this was the left-hand navigation, as this was generated using views, but we needed some quite clever css to happen with levels, so we could color code depending on which section you were in, how deep you were and how far an item was from the page you were currently on.
There was also a lot of research to be done with regards to the site, as it was originally developed by another team, and so there were things happening which we would not have normally done as part of our own process', so these needed to be found to prevent us stumbling over them at a later date