RelatedContent enables site maintainers to easily select on a per-node basis what nodes should be displayed along with it. Nodes that are available for selection are provided by one or more views, provided by the Views module. How the nodes are displayed is configurable, as well as themeable. The module also provide a small but powerful API for advanced users.
Some examples of what can be accomplished with the module:
The module can be used to embed into a node's body the teasers or bodies of nodes with related content.
In conjunction with the Simplenews module, RelatedContent can be used to compile newsletters out of already existing nodes.
Using its API, the module can made to display a block with content related to the node currently being viewed.
This module allows you to specify content type(s) as being a block. This allows the content managers of the site to edit the block text and title without having to access the block administration page. Users only need edit access to that node in order to edit it.
It is very handy to create a simple block content type and enable this content type for blocks and use these in place of the normal 'add block' functionality.
Now supports translatable content (Contrent translation with i18n and Entity Translation)
If Content Translation is enabled, then only a single node block per translation set is exposed and the node from the translation set with the appropriate language is loaded into the block.
Other modules
There are several other modules and approaches that allow nodes to be presented as a block. See a comparison at http://groups.drupal.org/node/93499
Drupal 7
The Drupal 7 version of this module enables the use of view modes. This gives the user even greater control over customizing the output of the node block. Default view modes and links display can now be assigned per content type and then overridden at block/node level.
A simple module which allows you to create menus from image files. Supports title (displayed when hovering over a menu item), alt text, weights and optional mouseover behaviour.
Since the permission system only lets the admin allow/disallow creation of content types and can't specify WHERE they can be used, this module tries to solve that problem.
New to 5.x, country_select module. This module makes use of the country/province data created for the addresses module to create country/province dropdowns for all countries in the world. Requires the activeselect module to work.
This module is a good solution for Drupal 5 users. Those wishing to have an address module in Drupal 6 might consider the location or addresses module. At this stage there is no Drupal 6 version of this module.
The 2.4 version has an option to save content in location module format. This provides location module upgrading provided you edit the nodes you want to upgrade.