Unless you play in the search engine marketing arena, you may not be aware of Google’s KeyWord Finder tool and the extent of its awesomeness.
In SEM, it’s used for finding the low cost, high traffic keywords to target. It is based on actual searches – spelling errors and weirdness and all.
As well as SEM, it’s great to work out how to position your copy. What are the words your audience are using? You may use jargon, but if your audience doesn’t use the same terms you won’t be found via search engines. And we all want to be found.
Looking at the related keywords can also give you topic ideas to write about. Or, you can do what I used to get distracted by when keywording SEM campaigns: see what people actually search. Be warned though, it’s often NSFW and will have you thinking WTF?!?