The digital age has opened up a number of opportunities to learn about individual differences in language utilization. My collaborators and I have created a technique and written some software to allow researchers to extract individual differences in the ways people use concepts.
The method is called the Contrast Analysis of Semantic Similarity (CASS). It compares semantic structure of multiple text documents (e.g., from different people or from different sources). See the www.casstools.org website for a full description and download instructions. I also recommend looking into BEAGLE, LIWC, and LSA.
For a general overview of how language is becoming a key object of interest in personality and social psychology, check out this brief online article that I wrote with Tal Yarkoni.