I came across a neat Google tool which allow one to examine keywords and find out the search value of keywords.
As can be seen in the screenshot, the tool give an indication of relative search volume and how much advertiser competition there is for the keywords.
This screenshot also show that it is possible to examine search trends for specific keywords.
It is also possible to examine estimated costs to post advertisements liked to certain keywords.
Quite a useful tool if you are trying to hit a specific target audience.