For years, Yahoo's (a.k.a. Overture's ) keyword suggestion tool has been a Holy Grail of sorts in terms of researching potential target search terms.
Recently, Yahoo decided to completely disable this tool, leaving many SEO folks in a state of keyword limbo. Discerning webmasters will tell you that this is essentially a non-issue considering that the folks over at Yahoo haven't update the Overture keyword tool data since early in 2007, making the tool an outdated resource at best.
Still, industry mouthpieces like SEO Book's Aaron Wall have already let their opinions be heard regarding the matter (his negative standpoint is no surprise, given that Yahoo's actions have rendered his proprietary search tool null and void).
Now there are some rumors that Yahoo will release an enhanced version of their keyword research tool as part of their "
Panama" upgrade to the current Yahoo Search Marketing platform, but for the time being, webmasters will have to play the hand that's been dealt to them. Fortunately, we still have some tools available to us (WordTracker, KeywordDiscovery, and Google Adwords' tool come to mind) and perhaps more importantly, we should all keep in mind that none of these tools is %100 accurate anyway and should only be used as a gauge.
Nothing less, nothing more.