Rank

Pagerank Checker, will assist you in checking:

Domain Age, Alexa Backlinks, Google Indexed Pages, Delicious Links,
Compete Rank, W3C Validator, Google Bot Last Visit, Google Backlinks,
Yahoo, Directory Listing, Yahoo Indexed Pages, Digg Links, Technorati Rank,
and Site Value.

What is Pagerank?

PageRank is a link analysis algorithm, named after Larry Page[1] and used by the Google Internet search engine, that assigns a numerical weighting to each element of a hyperlinked set of documents, such as the World Wide Web, with the purpose of "measuring" its relative importance within the set. The algorithm may be applied to any collection of entities with reciprocal quotations and references. The numerical weight that it assigns to any given element E is referred to as the PageRank of E and denoted by PR(E).

Source: http://en.wikipedia.org/wiki/PageRank