Views

This module provides an easy way to import previously exported Views definitions.

A "sustainable" theme is one that can grow seemingly effortlessly as the site grows. It saves time reducing theme work in the long term, and allows developers to change and add new sections that just "look right" right away.
Agenda

Using the custom theme of a large website as an example, I will go over:

This module provides two additional Views display plugins, "Profile" and "Node content". These displays do not display on a page but get "attached" to either a user page or nodes of specified types. These views are not stored with the user or node, the way viewreference.module would, so they can be globally-reconfigured.

The node content display can be reordered on the "Manage fields" tab if CCK is enabled. If not, it will have a weight of 10 so it floats to the bottom of the node.
Usage tips

Allows users to create named relationships between each other. It is the basic building block for a social networking site, or any site where users are aware of one another, and communicate.

There are many features on offer. It'd be worth your while to check it out.

Admins create relationship types (friend, coworker, etc). Relationship types can be setup to be one-way or mutual. If a relationship type is one-way (subscriber) only the requester is shown as relating to the requestee. Relationship types can also be set as needing or not needing approval.

The migrate module provides a flexible framework for migrating content into Drupal from other sources (e.g., when converting a web site from another CMS to Drupal). Out-of-the-box, support for creating Drupal nodes, users, and comments is included - hooks permit migration of other types of content.

In addition to performing the creation of Drupal objects from arbitrary data, migrate helps with the methodology of data migration:

The overall purpose of the Nodereference Explorer module is to provide a comfortable and user-friendly way of referencing content. Content authors should be able to link internal arbitrary nodes, e. g. content types such as pages, stories, news, images etc., to each other. Typical use-cases are for instance: