What does Google say about it's Pagerank System?
http://www.google.com/technology/index.html

PageRank and Linking Technology
http://www.google.com/corporate/tech.html
Advanced search technology that involves a series of simultaneous calculations typically occurring in under half a second-without human intervention. (Don't you just love it!)

The Google Pagerank Algorithm and How It Works?
by Ian Rogers
http://www.iprcom.com/papers/pagerank/index.html

Measuring PageRank
http://www.top25web.com/pagerank.php
This really cool tool from top25web.com details the pagerank on multiple URLs at one time rather than having to check Pagerank one URL at a time.

BackLink Builder
http://www.webconfs.com/backlink-builder.php
This tool is one of my staple tools in successful linking campaigns. Instead of querying each phrase one at a time, the 'inbound link exchange builder' tool queries numerous keyword searches at one time. The list of results give you websites to solicit for smooth link ups.

Link Popularity Checker
http://www.linkpopularitycheck.com/
This service will quickly compare your link popularity across three search engines.

Link Popularity Checker
http://www.linkpopularitycheck.com/
This service will quickly compare your link popularity across three search engines.

Link Popularity Checker
http://www.marketleap.com/publinkpop/
How many links are pointing at your web site and who are they? Due to the dynamic nature of the web, results reported are collected live each time a request is made.

Search Engine Saturation
http://www.marketleap.com/siteindex/default.htm
How many of your web site's pages do the search engines have in their indexes? Once you know what the search engine spiders see, you will know which pages need attention to get them included.

Link Popularity
http://www.linkpopularity.com/
This free service allows you to query Google, Altavista, and Hotbot and reports on link popularity.

Link Survey is a link popularity tool.
http://www.linksurvey.com
Detailed link strategies of your competitors, locating potential link partners, and get link popularity reports on all inbound links are provided by this downloadable software product. The link popularity of MULTIPLE relative websites can be checked simultaneously and the results can be exported and merged into a spreadsheet, text file or HTML file.

Google Backlinks Checker
http://www.searchbliss.com/seo-tools/google-backlinks.asp
How many back links do you have in the Google data center barrels?

Measuring Link Popularity
http://www.searchenginewatch.com/webmasters/popularity.html
How popular is your web site? Directions on how to measure link popularity at the popular crawler-based search engines.

Links To You
http://www.linkstoyou.com/
Service offering to generate links to your web site free.

Link Me
http://www.linkme.com/
Link management system allows a webmaster to easily manage a link exchange program.

University of Toronto's Web Site Theme Identification Tool
http://www.cs.toronto.edu/db/topic/
This fabulous tool identifies your 'web page reputation' in Altavista.

Link Reputation Analysis
http://www.optilinksoftware.com/
So you have oodles of links pointing at you. If they are not relevant to the theme of your web site they will do more harm than good.

TEAM: W3C Link Checker
http://validator.w3.org/checklink

TEAM: Webconfs Backlink Builder
http://www.webconfs.com/

On The Lighter Side Of Google Technology

The Technology Behind Google's Great Results
http://www.google.com/technology/pigeonrank.html
"The heart of Google's search technology is PigeonRank TM, a system for ranking web pages developed by Google founders Larry Page and Sergey Brin at Stanford University."