By entering a keyword related to your market is shows other related terms (singular and plural) and it analyzes the competition for every one of them.
Useful keyword tools:
WordTrakcer – most popular online keyword research service, offers advanced keyword research and suggestions.
KeywordElite – is desktop tool with many keyword research features. This tool will collect you keywords from various places into numbers of thousands. It is used by most top SEO and PPC marketers.
