From http://www.codeguru.com/faq.php

What are the "reputations" in the forums
The CodeGuru site allows for a number of different ratings. Reputations is one of
these ratings. Reputations are points gained or lost on individual posts within the
discussion forums. Because these are tied to individual posts, they reflect back on
the person who made the post, thus giving them a reputation.

Your reputation can have positive and negative changes. Better yet, as a member
of CodeGuru, you can add to others' reputations. If someone gives you a great
answer, you can give them a positive reputation point(s) as a thanks. If someone
blasts a thread with an off-topic post or with negative comments, you can give
them a negative reputation. With time, these reputations will help the "star
posters" rise and the people who only provide noise to become visible as well. Is
it possible to cheat the system? Yes, but as it was in the old days, the forum
moderators and I are aware of many of the ways to cheat the system and will
take appropriate actions.

Reputations are indicated by a small graphic. The more positive your reputation,
the more visible the graphic will become. This will be displayed by all your posts
and in your profile. To add to someone's reputation, you will click a small scale
graphic on the upper, right area of the post. It looks like a scale or balance. This
will result in a pop-up window as shown in Figure 1.


Figure 1: The Reputations window.

In this window, you can either give a positive point (approve) or negative
(disapprove). You should also add a comment on why you approve or disapprove.
If this is your post, you'll be able to see the reputation points you have by clicking
on the scale;

Reputations come with rules. You only get a certain number of points each day, so
use them only for the best postings and responses. Right now, this is 6 times per
day that points can be given.

There is reputation POWER. Power is the number of points you give each time.
This starts at 1 point, but increases based on a number of criteria such as posts,
tenure, and your own reputation. When you give negative points, they are at half
of your power level.


Here are some other rules and settings for reputations(which are subject to
change):

You must give reputations to a number of different people before you can
come back to the same person again. No giving just one person all your points!

For every 1000 posts at CodeGuru (that are counted—so not including chitchat),
you get an extra point of reputation POWER.

For every year you have been with CodeGuru, you get an extra point of repuation
POWER.

For every 1000 points of reputation you receive, you get an extra point of
repuation POWER.

While you can use reputation points today, your reputations will not be applied
until the following conditions are met:

You must have posted at least 25 counted messages to CodeGuru.

There was a rule that you must have 5 points of reputation yourself before your
points will count (you start with 5).