I love looking at site analytics, and one of the most interesting and useful things to look at are search terms people use to find your site. So you can really look at what topics people are interested in. I had a look at how people come to my site via Google, grabbed the top 20 phrases and put them into Wordle. I didn’t weight the most commonly used ones against the 20th most commonly used one, but this still gives a good representation of the key themes people search for, that I write about.