.copy a {
[your css]
}

for the base link colour.

As far as the "Copyright" I feel that you are extremely generous in allowing it to be removed, it is a very small price to pay for a quality software program such as PunBB. If someone feels they have to remove the copyright then I feel they should PAY for that privilege. I personally have "dimmed" (#C0C0C0) the copyright information, however it is still visible and clickable (http://iwcomm.com/forums/) but I would not think of removing the credit for someone else's hard work!

I like this idea and am using it on my client's forum.  My only problem is that I cannot figure out how to make the link for PunBB dim. 

I created this CSS:

.copy {
color: #b4b4b4;
text-align: right;
}

.copy a:link, .copy a:visited {
color: #b4b4b4;
text-decoration: none;
}

.copy a:focus, .copy a:hover, .copy a:active {
color: #b4b4b4;
text-decoration: none;
}

And I placed this in the footer.php:

<p class="copy">Powered by <a class="copy" href="http://www.punbb.org/">PunBB</a> ....

And the link is still the default blue.

Where did you change the color ?
In footer.php,main.tpl,style.css or style_cs.css ?

Thank you

TESTIMONIAL
I have been searching for sometime to find a forum that would integrate 100% with existing website designs, but have been unsuccessful until now! I have tried everything from phpBB to WSN but always ran into problems attempting to get a seamless match to an existing website. Finally, it works!

Thanks For All The Hard Work!!