Free Keyword Searching tools

Free Keyword discovery tools

Digital Point Keyword Research Tool
Google Suggest
Related Pages
Good Keywords
Overture Inventory

Payed Keyword Searching tools :

Wordtracker - free trial also available - Discover the best keywords to
target on your website
Keyword Discovery- free trial also available - Find the best keywords for
your website

Website Analysis tools :

Google Analytics
StatCounter
WebTrends
Omniture
OneStat.com
WebSTAT
Site Meter
Awstats
Fireclick
ClickTracks

Site ranking free tools:

www.alexa.com
www.compete.com
www.ranking.com
www.nielsen-netratings.com/

Keyword density checker tools:

www.ranks.nl
www.keyworddensity.com
www.seochat.com/seo-tools/keyword-density
http://www.seobench.com/keyword-density-analyzer/
http://www.stargeek.com/keyword_density.php
http://www.virtualpromote.com/tools/keyword-analyzer/
www.golexa.com/

Back link Checker:

http://www.backlinkwatch.com/
http://www.webconfs.com/anchor-text-analysis.php
http://www.prsearch.biz/inbx.php

Blog & RSS Feed Analyzing tools:

Pheedo
MeasureMap
Feedburner
Performancing

Link partner searching tools:

Link Partner Finder
Find Link Partners from zebonline

Tools which you may find helpful:

Link Popularity Check - quick and easy to use web tool from Marketleap.
OptiLink Software is a link analysis program that reveals how top ranked pages achieved their search engine rankings.
Zeus Internet Robot - automatic reciprocal link generator and link directory creator from Cyber-robotics.
Arelis Link Builder - reciprocal links solution from Axandra/Voget Selbach Enterprises GmbH