A few others to pile on further -
Keyword Research Tools
Spyfu (for competive research)
HitTail (for keyword referral reporting)
Spyfu is pretty good with matching up with what you described. But based on my experiences I only use competitor meta tags and keywords for "idea" research. Best way I can describe using someone else's keyword research for your own keywords .... kind of like the blind leading the blind often unless it is a rare case where the seo who did the work well. But it can be a good brainstorming process to go through - just research further (popularity/competitiveness) beyond another competitor targeting a keyword.
Anyone else, please feel free to keep adding on what you use or anything else helpful.