User engagement

Shows a user's most used taxonomy terms on the profile page.

Evaluate a users expertise and display the result on the user's profile page.

The User Activity module calculates an activity index based on a user's logins, page impressions, created nodes and comments.
The weight for each value is adjustable by an administrator.
It provides an activity-o-meter on the user's profile page, a block with the most active users and an overview page of users sorted by activity.

The user Visits module tracks visits and referrer from other users on a user's profile page.

Community-managed taxonomy (CMT) opens categorization of content to the site's community.

Welcome to simple_karma!

This module allows people to give good or bad karma, based on their comments on the web site. It's fully configurable, comments can be buried if their karma is too low, user roles can change according to user's karma values, and so on. It all works through (fully degradable) Javascript/Ajax.

NOTE: this module is now obsolete. It is replaced by Extra Voting Forms and User Karma, which are derived from simple_karma but are based on the fantastic VotingAPI (which means you can use "views" with them).