Start Advertising with Yahoo! Search Marketing in 5 Simple Steps

Similar to the External tool at AdWords, you may use the keyword suggestion tool of Yahoo! Search Marketing without actually signing up for the service. Just choose the Self Serve option, and name the geographic location you would like to target, the time zone in which the website would operate in ( this might be irrelevant for some ), fine tune the location(s) and you may continue to the keyword suggestions.
Yahoo! Search Marketing is the only tool that uses Yahoo! Search data - apart of the suggestions you would get from their search results pages. Similar to, albeit less functional than the free external tool of AdWords, you will be requested to input up to 50 initial keywords of your choice before the system would provide you with suggestions.
The appearing list will show both your selection and the related terms, provide an estimated number of searches made for the phrase, an average of many months, which can range from as low as about 10, to as high as 200.000+. Also, the tool will display an exclamation mark for those keywords it suggests to be a bit too high on search volume ( in other words: too generic ) to be effective for paid advertising. This message of course can mean completely different things in the creation of an informative, a commercial and an entertainment oriented website.
Further options and refining is available outside the program, including example ads for the keywords you chose. Most of them actual live listings of possible competitors.
Useful, similar in functionality to AdWords, free version somewhat limited in certain areas.
Checking it against the data from Google is advised
Checking it against the data from Google is advised