There aren't that many companies out there that offer liquid cooling products which you can purchase separately. There's a handful of them.
One of them is the German based Alphacool. Recently they introduced a new CPU block called the Alphacool HF 38 Niagara.
This new water-block is designed for Socket 1366 processor, aka Nehalem aka Core i7. A high-end liquid cooling CPU block priced fairly. Let's check it out at the URL right here.