Keyword Discovery Tools

Here is a list of 15 keyword tools with links to get you started. Includes a mix of free and paid tools and a few different types. There are free trials for most of the paid tools. Enjoy and submit feedback and suggestions in the comments of the Keyword Discovery Tools Blog Post here.

Logos and linksKeyword toolsCommentsFree or Paid?
Long Tail ProLong Tail ProMy NEW FAVORITE SEO TOOL. This tool that includes the ability to generate keywords based on seed keywords, to see who is ranking for your target keywords and how strong they are. Allows you to target keywords with less entrenched competition. Also you can check Google rankings with this tool.One time payment - Software Download
market samurai keyword toolMarket SamuraiSoftware download. One of the standby keyword tools. No subscription required.One time payment, free trial available (and free version includes keyword research)
SEM Rush keyword toolSEMRushA variety of keyword tools and competitive keyword research. Unique capability - it can discover what keywords you rank for (versus you needing to input them)Subscription; Free limited account available
Google External Keyword ToolGoogle External Keyword ToolFree and easy to use; a great starting point for anyone. Includes search volume and competitive estimates and trends over time; includes local search estimates. Easily export your keyword lists to a spreadsheet or word-processing software.Free
Google Adwords Keyword ToolGoogle Adwords Keyword ToolThe same as the Google External Keyword Tool above except this requires an Adwords account and allows you to automatically move keywords into your Adwords campaigns.Almost free; $5 to start an Adwords account
Word TrackerGenerate keywords for organic and PPC campaigns, research online markets, find niche opportunities.Subscription; free trial available
Keyword discovery keyword toolKeyword DiscoveryKeyword database from over 200 search engines, keyword research tools (trends, competitors, keyword effectiveness, PPC bids), competitive analysis, options to access their API and save your data into projects.Subscription; free trial available
Wordstream keyword toolWord StreamRange from keyword discovery, research and analysis to keyword organization and actual paid and natural search marketing activity.Paid with free trial version
spy fu keyword toolSpy FuOnline competitive keyword research tool, includes PPC infoPaid but you can run a free report with some limits on the site
Google search-based keyword toolGoogle Search-based Keyword ToolGenerates keyword and landing page ideas relevant and specific to your website. Helps you identify additional advertising opportunities that aren't currently being used in your AdWords ad campaigns. Includes competition estimates, suggested bids and is based on actual search data for your language and geography.Free with Adwords account
Google trends keyword toolGoogle TrendsCurrent keywords trending in Google's search engineFree
Google-insights-for-search-keyword-toolGoogle Insights for SearchBased on your search terms, plot keyword search trends by region, time period and optionally, by category (home & garden, computers & internet, etc.)Free
Microsoft advertising intelligence excel pluginMicrosoft Advertising Intelligence Excel PluginBuild out lists of suggested keywords based on Bing and MSN query data, including: relevance, volume, cost history, demographic and geographic.Free
Rapid keyword toolRapid Keyword SoftwareA variety of Keyword Finders (Overture Keyword Suggestion too, meta tag parser for web pages, Yahoo related keywords, Google Suggest, typo generator, Metacrawler related keywords), Competition Analyzers, Keyword Management Tools and includes a Scratch Pad functionality.Paid software for download; free trial available
Wordze keyword toolWordzeMeta Search Tool (uses meta search data and Google data to find keywords), Wordrank Tool (uses InLink, InTitle and other metrics to profile competition), Adwords Spy and Search Trends.Subscription; free trial available
SearchMetrics RapidOnline tool, includes PPC infoPaid, free partial version available on the site
Keyword SpyOnline tool, includes PPC infoPaid with some free info available
Key Compete keyword toolKey CompeteOnline keyword research tool. Identifies keywords your competitors are using in their PPC campaigns and who's bidding on your keywords. Also include keyword search estimates, Web site and keyword ratings, Web site and keyword "Watch Reports", Competition Reports and Long Tail Reports.Update: NOT SURE IF KEYCOMPETE STILL EXISTS.. Subscription; One-day paid trial available
See the SEO Toolkits or
Enterprise SEO Platforms (below) which can include keyword research tools
Bonus Keyword Tool:
keyword eye keyword toolKeyword EyeShows related keywords in a word cloud - give it a tryFree
YouTube Keyword ToolSee what people are searching for on YouTubeFree