The Resundering is Pueblo-enhanced, which means a little extra in the way of graphical content for those who use Pueblo. Which is why we recommend it. It can be found here.
A lot of people prefer ZMud. It has automatic mapping and lots of other extras. It costs money though. You can get it here.
An oldie. Good if you're a Unix or OS X type. It's here.
Whichever client you use, the address to connect to is:
resundering.net 5000