I happened to come across this adsense ad: and visited the first website, digg4it.com. If you take some minute to go there, you'll see that it is just a search field. For any query it gives you a page with LOTS of AdSense ads. No content at all, just ads. Watch for auto-generated subdirectory names in the address bar (evidently used to trick AdSense bot into displaying relevant ads) I wonder if the website should be reported to AdSense regarding TOS violation, and probably even Adwords TOS violation since it is being promoted via AdSense network as well.
this is the second time this week i see a thread about digg4it ... They should send u thank's email for giving them a link back and advertising for them ....
I don't think backlinks from DP get indexed by SE's. But anyway, it's just easier to click on a link than to type it manually.