Two of the top boards right now are the Abit NF7-S and the Asus A7N8X. They both offer NVIDIA SoundStorm 5.1 digital sound Serial ATA150 ports, and support for the newest Barton core CPU's.
That would be the ultimatly pointless ACR {Advanced Communication Riser} the only thing that uses these slots are a few NIC's and I have never seen one to use ACR.