Rack + IP trading sites

Anyone know of good sites where you can trade rack space and IP bandwidth? I am looking for rack space and IP in London and trade if for space and IP in one of our US datacenters. I found lots of sites for trading raw capacity, but can't seem to find a good site for trading space with IP.

<> Co Founder, CTO Nathan Stratton BroadVoice, Inc. nathan at robotics.net Talk IS Cheap http://www.robotics.net http://www.broadvoice.com