We often use Panels to build node page layouts, because it enables a vast range of options to show content in various sections of the page. In addition, you can develop a custom plugin for Panels, which brings ultimate flexibility. I took that route when I needed to display an icon next to the node’s title to indicate whether it is published or not.
Organic Groups is one of the most powerful social networking modules for Drupal. It allows users to maintain groups. The managers of these groups can control who can join, or post or view content in their groups.
Essentially, these groups can act as microsites inside the site; they have their own user list, content, and access control. For example, a football site might want to maintain groups for football teams, and post news and announcements that are relevant to the team in the team's group. The players would then join the OG group of their team. When players visit the group's page, they would see only that team's content (nodes, technically).
When setting up content types on a more involved site, a developer could easily end up with having an enormous list of fields in one single content type. When this happens, I tend to pause for a second, and think through whether there is any way to consolidate that list. Chances are, I find a field or two whose values either depend on other fields or can be generated without user input. These are the exact scenarios where the Computed Field module can be a great choice.
Although the CCK3 module had never seen a full release, it was still worth upgrading Drupal 6 sites from CCK2 to CCK3, because the latter added a very compelling tool to CCK's arsenal: Multigroups. This feature allowed users to group several fields together, and enter multiple values into that set of fields as a whole by repeating the field group whenever a new value is added.
At Urban Insight, the Kaltura video platform is one of our favorite video hosting services because it has excellent support for mobile devices. Uploaded videos can be converted to mobile format, and when Kaltura code is embedded in a site, videos play nicely on virtually any mobile device. Unfortunately, the Kaltura Drupal module does not currently provide effortless support for the Kaltura HTML5 player feature.