In the category of variables I never thought to correlate, here's a study from a couple of months ago that examined the diffusion of Internet broadband and its association with voter turnout and campaign contributions. As you can tell from the abstract, he finds broadband expansion is related to greater turnout and an increase in donated dollars, more of it going to Democrats who are hypothesized to have a stronger online presence.
More to the point of this blog, he finds broadband availability is associated with greater political knowledge and "the promotion of liberal values." Let's take a closer look at his evidence. Like a lot of economics papers, this one is full of formulas and statistical wizardry. Ignore it. The paper does a nice job of measuring political knowledge across several survey waves with no fewer than six items in one wave to 17 in another.I could never find a measure of how well the items hung together, either in terms of reliability/internal consistency (Cronbach's alpha) or factor analysis. Perhaps that's not normal in economics, while in political research it would be expected. Again, quibbles. There's some interesting stuff late in the paper that's of interest to folks doing political communication research, especially tables 13 and 14. If I read Table 14 correctly, and I'm not sure I do, the number of ISPs (broadband) is negatively related to watching Fox News and the news on CBS. The other sources of TV news are not statistically significant. Broadband seems to have negatively influences watching TV news both via traditional broadcast networks and cable channels (Table 13) but is unrelated to other news media exposure items.
Again, it's a complicated paper and I've just started getting into it, but there's probably more her of use than you see at first blush -- if you can work through the economics and dismal science language.