The SEOmoz keyword difficulty tool does a great job at figuring out how difficult it is to rank for a particular phrase. It uses data search data that the user provides via Overture to figure out the competition level.
SEOPal is all about ranking the top SEO factors. Everything is created and voted on by the SEOPal community. Here you can learn Whitehat, Blackhat, On-page, Off-page or whatever else suits you best!