http://www.tomsguide.com/us/killer-m1-nic,review-1083.html
Kinda interesting. This is a NIC that offloads the TCP/IP stack to the NIC itself instead of letting the main CPU take the load. It had a 400 MHZ NPU (network processing unit) with 64mb of RAM and had a heat sink.
Some of the benefits are:
Faster ping times and transfer times (although they didn't really test transfer times). The ping times increase about 15-30ms.
Because they were focusing on gaming (for some reason) they saw about a 10% increase in frame rates
It has linux installed on the card (would be fun to hack that)
And you can put a firewall on the card to act has a hardware firewall (really cool)
USB port on the card itself so you can perform transfers directly to the storage medium
And other smaller features