Friend

This module has been abandoned. You probably should read review of buddylist like modules.

Allows you to add members to your friends list. Also has an invite friend section which will send an email inviting them to the site.

There's also a corkboard system which allow friends to post messages to your corkboard.
This is a very basic friend module for community sites similar to buddylist but only for 6.x as I don't know when or if buddylist will be ported over to 6.x.

You probably want to also download the Notice Feed module (http://drupal.org/project/notice) to get your News feed and mini-feeds (similar to the Facebook feeds).

Current Features
- add/remove members to friends
- post corkboard message to friends when viewing their profile page
- invite friends to join site via form which emails them
- when an invited friend joins the site then that person is automatically added to the member that invited them.
- friend relationship is reciprocal (A adds B to list => A is also added to B's list)
- privacy settings for what is viewable to friends or friend lists.

Note:
This module is only for Drupal 6.x , there are no plans to create a 5.x version. Please use the buddylist module for 5.x