Dot what?
There's been a lot of talk lately about ICANN's preliminary approval of some new top level Internet domains (.cat, .jobs, .mobi, .post, .travel, and .xxx), some more controversial than others. I've followed the various social and political debates only peripherally, but it seems like this could lead to a broader trend of sites assigning themselves to categories like jobs and travel.
Using the Site Search feature, you can narrow searches to a specific website [admissions site:www.mit.edu]. But what many people don't know is you can also use Site Search to narrow searches to a top level domain, which I found handy during tax season: [1099 site:gov].
Right now, Site Search can be used for top level domains (.org, .edu, .mil, .com, and .net), as well as country domains like .it (Italy) or .sz (Swaziland). As more of these come into play, topic-specific searching could become even easier.