This particular domain receives its links from PR7 pages giving it it's PR6. They can be found using the yahoo site explore tool:
http://siteexplorer.search.yahoo.com...&bwmf=s&bwmo=d
You could either use a program like scrapebox or Seo Spyglass to quickly obtain the PR of all the inbound links. This is also doable by hand, of course.
If you want this link for it's traffic, don't bother, you are correct that it doesn't have much. This link is meant to increase your pagerank and thus your trust and position in the serp's, nothing more, nothing less.