Given the current DEFCON 1 level of anxiety about recommendation letters, and my belief that more transparency is usually a good thing, I thought it would be informative to assemble a word cloud of about 10 years of recommendation letters written for undergraduates applying to graduate schools or fellowships (with names and schools omitted).
As you can see, the top three themes are "research", "project", and "work" indicating that the letters are highly weighted towards what students have actually accomplished, rather than just pure intellectual firepower. The cloud for graduate students applying to postdoctoral positions would be more biased towards words like "thesis" and "papers", but would again emphasize what one has done, not how intelligent one is. So, if you are a student thinking about graduate school, you should make sure you get involved in research, and, when you do, make sure you get something done!
