It has been brought up several times, so I thought I'd like to make a public announcement especially directed toward newcomers who are also planning on using some of the skins that are freely contributed and supported by skin creators here.
Some creators have specified certain usage policies regarding their skins. We ask that you please respect their terms, and such as giving credit where it is due. Even if you edited the skin with graphics, or different CSS, the original skin was still created by someone, so give them credit if they ask for it, a simple linkback is all they ask.
It may also be unclear to some people what their terms are, so I'd like to explain for those who don't know, what the Creative Commons licenses state, here are their explanations.
So for example, a Attribution Non-commercial Share Alike (by-nc-sa) License:
This license lets others remix, tweak, and build upon your work non-commercially, as long as they credit you and license their new creations under the identical terms. Others can download and redistribute your work just like the by-nc-nd license, but they can also translate, make remixes, and produce new stories based on your work. All new work based on yours will carry the same license, so any derivatives will also be non-commercial in nature.
Meaning that you are allowed to edit and change the skin and use it if your site is non-commercial as long as you credit the author in the original way they specified (i.e. linkback).