By KEI, I assume that you mean: Keyword Effitiveness Index, the value of targeting a specific keyword in taking into account the number of searches for the phrase and the competition that it has in ranking for it.
Tool:
Keyword Selector Tool
Forum discussion with the owner of the site / tool:
http://www.marketingchat.org/forum/kei-tool-t1286.html
What about
Keyword services for professional search engine optimization
Keyword Discovery - Advanced keyword research tool and search term suggestion tool
and their tools?