I think the most important data that is difficult to obtain is a history of which links people click on for each search query term. I think that's really the special sauce that Google has that others do not. There is a catch-22 where you need a lot of users to get the data but you can't get the users without the data. Initially Google pulled ahead with inbound link counting, but anyone can clone that. It's the click data that's missing.

hah, that one is easy. People click the one at the top the most, then nr 2, after that nr 3, etc you see the pattern?

Google was epic when it started but quickly ended up indexing it self in a near closed loop. Everyone else was not important, it was all about the picture in front of them that was really just a mirror. Everyone stopped making home pages, forums and weblogs because it just doesn't make sense to do it.

Shit, people looking to buy something talking among their own before doing the purchase? KILL IT WITH FIRE!

Assuming someone has ever used that link you should have that data as well and with potentially even more relevance than google because you can see which pages are most often visited through external links.