I sent a PM, but I'll explain it for everyone who is interested.
Each time we buy a domain , we go back and look at its link profile, index profile & history. If something is niche specific that we like and want to add to our repository of websites we attempt to rebuild its old pages. This has been highly effective for us bringing back niche-specific traffic.
For instance, website #20 was a "Financial help" website with topics about things like term life insurance, annuities, mutual funds, stocks and the like. We rebuilt 15 to 20 pages on the website that it had before the former owner lost it. After a week or so, we started to see traffic for keywords relating to these topics. In this case, the terms are extremely high CPC, so when you get a post on that site, you know that you've got a good chance to see some quality traffic to your article(s) and then as click throughs.