Herramientas de SEO, SEM y Analítica Web

Spider Bots


Spider (Feedthebot), Spider Simulator (Webconfs), Spider (Linkvendor), Search Engine Simulator (Webmaster Toolkit)

Xenu - Detect broken links and create XML sitemaps
Fetch as Google Bot - Simulate Google Bot's crawl on a website
GSite Crawler - Create XML sitemaps

Plugins for Firefox

HTML Code Analysis
Firebug, Web Developer Toolbar for Firefox

SEO Toolbars
Mozbar, SEO for Firefox, SEO Quake, Search Status

Multi Links - Massively copy clean URLs from Google's SERP
AutoPager - View many Google's SERPs in a single window
iMacros - Automatize repetitive tasks in HTML pages (ex. fill forms).
NoDoFollow - Highlight links with nofollow.
Link Checker - Diagnose valid and broken links.
Rank Checker - Detect positions of a webpage in Google, Yahoo! and Bing.
FoxyProxy - Change proxy to navigate anonymously.
View Cookies - Discover cookies installed by any website.

Other Resources

SEO:
Google SERP Snippet Optimization Tool - Preview of metadescriptions in Google's SERP
WayBack Machine - Historical archive of Internet
My IP Neighbors / Blacklist Check - Analyze IP neighbourhood
Domain Age (WebConfs) / Domain Age Checker - Calculate domains' agen

SEM:
Lower Your Bid Price - Reduce CPC in Google Adwords campaigns
Magic Adwords Button - Excel application to analyze Google Adwords campaigns

Social CRM:
Retweet Follow, Netvibes, Hootsuite, TweetDeck