Well I am still awaiting a reply from Jason Katzenback so I spent some time browsing the forums.
There is some hardcore analysis of Portal Feeder happening on Phil Wiley's forum.
Now this is not 100% confirms, but a few people claim that Portal Feeder leaves a massive footprint.
To find Portal Feeder sites, you just search for them on MSN
I have no idea whether this is some default configuration, or how they found a first site (maybe searching for article text).
Whatever tool made the sites, I must admit I don't like the numbered articles.
portal feeder , VRE , Virtual Real Estate , niche website