I’d never seen this site before but came across it while reading a comment to seoroundtable’s post about keyphrases that you should think twice about before trying to conquer. The site is called RankPulse and it ranks the top 1000 most competitive keywords. Good site to find out what to stay away from!
Also, as a side note, I saw on a variety of blogs this morning including Inside AdWords that they have new tutorials available on how to use the AdWords Editor Tool. I tried the tool and was not that thrilled with it, but am thinking about looking at the tutorials to a see if there was anything I missed that would make it more attractive to use.