Keyword Tools

There's one tool in here that I had never heard of, so this site caught my attention... rest of the list could be useful for someone.

Keyword Verification (Search Engine Placement Check - Marketleap Search Engine Verification Tool) - checks to see if your site is in the top three pages of a search engine result for a specific keyword
Keyword Density Analyser (Mark Horrell - Keyword density analyser) - another SEO tools for keywords
Keyword Cloud (Keyword Cloud - SEO Tools - Search Engine Optimization, Google Optimization) - a visual representation of keywords used on a website
Keyword Density (Keyword Density - SEO Tools - Search Engine Optimization, Google Optimization) - another SEO tool for checking keyword density
Keyword Difficulty Check (Keyword Difficulty Check - SEO Tools - Search Engine Optimization, Google Optimization) - see how difficult it would be to rank for specific keywords or phrases
Keyword Optimizer (Keyword Optimizer - SEO Tools - Search Engine Optimization, Google Optimization) - optimizer your keywords with this tool
Keyword Suggestion (Keyword Suggestion Tool) - Find related keywords matching your search

Courtesy of Digest - Keyword Tools | Black Hat SEO Digest