1. Webmaster tools ΒΆ

SEO tools for MSN, Yahoo, Google, etc.
MSN : http://webmaster.live.com
Google : http://www.google.com/webmasters/
Yahoo : http://siteexplorer.search.yahoo.com/
Ask : http://submissions.ask.com/ping?sitemap=http://www.yourdomain.com/sitemap.xml This is for submitting sitemap.xml only.

Whois service : http://whois.domaintools.com

[http]social meters check links in major social folksonomy sites such as del.ios.us
[http]Quark base
[http]Google analytics
[http]Technorati's blogg info
[http]Cube stat - v
[http]DNS scoop - negative for foregin (outside US) sites.

For web analysis and optimization:
http://www.websiteoptimization.com/services/analyze/
http://www.websiteoptimization.com/speed/tweak/css-sprites/ For using CSS technique in a graphic menu (AOL case).
http://www.websiteoptimization.com/speed/tweak/parallel/ For using parallel server for multi-threading by web browser.

For the reference:

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