Rand posted an update to a tool named keyword difficulty tool. The tool's name is pretty descriptive enough, it tells you how competitive a keyword is to rank for. There is great detail on how it works here and here.
I did a test on the term "seo blog" for no good reason. After waiting the specified amount of time, I was given a ton of details, which you can read in this pdf document (1.5MB) .
Last Week to Save on SES London Tickets!
Learn to engage customers and increase ROI by distributing your online marketing efforts across paid, owned & earned media. Join the leaders of today's digital marketing & advertising industry at SES London. Find out more ››
*Saver Rates expire this Friday, Dec 13.