found this:

Your Reputation Power is the number of points you give when you rep someone else, and is calculated as follows ;

Your Green (positive) Reputation Power is ;
.

* One point for every 1000 posts you have made.
* One point for every 250 points of reputation you have.
* One point for each 365 days you have been a member.

Your Red (negative) repping power is half of your green repping power.

For a rep to count you must have at least 10 points, and have made at least 1 post. Non counting reps are displayed as Grey.

You can give a maximum of 20 reputation "hits" per 24 hour period, and must rep at least five different people before you can rep the same person again (Administrators are exempt from these two limits).

A number of green & golden pips are used to show other users your reputation level. The first five pips are dull green, the next five are bright green, then you can have up to 10 golden pips (after that is currently a secret).

Each pip in it's color group has a set value.