Matt Mazur is a software developer who runs a site called LeanDomainSearch.com. He posted a sample on Namepros of his latest analysis of the .com zone file.
In theory, the more popular the topic, the more in demand those domain names are and the more valuable they should be to your portfolios.
He said, "I conducted the analysis by first calculating the top prefixes and suffixes and then working backwards to figure out what the topics were. For example, I looked at all of the domain names that ended with "spot", figured out what the topic was (ie, "car" in "carspot.com"), and then added up the totals to see which topics occurred most frequently. The results looked at the .com zone file specifically and did not look at other zone files, though the results should be fairly consistent."
Here are the top 15 results:
Check out the whole article and all the results at LeanDomainSearch.com