Spammers Are Great Keyword Sources - Here's How to Mine Them:
(Disclaimer: This post might seem a bit confusing if you just read it. You may have to click the links to see the process and fully get what I am talking about.)
The good thing about high ranking spam is that you know that the people who are doing it are probably both creative and focused on ROI, so you might be able to come up with a few good keyword ideas based on their research.
When you see a site in the search results that does not seem like it makes sense, it is probably there because either a spammer bought it, or the site has content management system errors which allow spammers to add content to the site. For example, SafeSurf.com is an authoritative site which was recently ranking for a competitive financial query, which seemed out of character with the nature of that site. So lets say you see one of those spam pages ranking in the search results. If you are doing keyword research and have ran out of topics you can look for footprints on these spam sites to find new ideas. As long as Google's algorithms place as much weight on authority domains as they do right now you are bound to find some people abusing that hole by placing hundreds or thousands of pages targeting expensive keywords on them.
For example, after I got the full URL of that SafeSurf page, I pulled off the file name, and looked for other things in that same folder inurl:spammydomain.com/spammyfolder/. In addition to domain related searches like inurl: many of the spam pages may have other footprints or signature text that you may want to look for.
If there are many results there you can further filter through the spammer's keywords by adding a keyword to your query. For example, search for keyword inurl:footprint.
As you can see, SafeSurf.com is a valuable highly rated website...or at least one which is offering many high value loan related keyword phrases!
Want to Mine PPC Accounts for Keywords Too? Here's How:
Another good idea for coming up with conversion / profit oriented keyword ideas is to go to the Clickbank marketplace, search for a topic related to your keywords (like weight loss, for example), see what top selling merchants match your topic, and then plug those URLs into KeyCompete.com or SpyFu to find related keywords.
You can then run that list of keywords through an Overture search suggestion scraper to get an estimate of search volume. Or put them in the Google Traffic Estimator with no bid prices to see the estimated bid prices AND projected AdWords ad click volume. Then sort those traffic estimator results by search volume or overall value to find the most important keywords and keyword phrases.
Extend Your Content:
If you write real content about the major keyword phrases covered by highly ranked mass spammers or profitable ads associated with top selling products, and then track your referral logs, you can come up with even more specific keyword topics to write about.