You can build your own vertical search engine using Topicle. Topicle is a platform for vertical search engines, rather as Ning is a platform for social networks and BricaBox is a platform for social content.
That’s about as exciting as I can make Topicle sound. It’s less of a platform than a veneer on top of the Google Custom Search platform. I set up a Custom Search engine about a year and a half ago. There’s a link to said engine in the sidebar of this blog, since it provides Directions Along the Changing Ways: it enables search of, not just this blog, but the whole happy Changing Way family of sites.
I did create a search engine for Boston at Topicle. I remain underwhelmed. It’s essentially a list of site URIs. Note that you (yes you) can edit the list.
The most interesting part of the exercise came when I tried to make the engine understand the Boston-ness of this blog. Posts I put in the Boston category should be searched. Posts I put in other categories (e.g., WordPress) should not be searched by the Boston engine.
So I included the Boston category by specifying the URI http://changingway.org/category/boston/. Although Topicle/Google accepted the URI, it doesn’t appear to do the corresponding search. I got similar results, or lack of results, when I included the feed for the Boston category.
I know that eclectic blogs like this one present problems for vertical search, but I think it’s a problem that vertical search engines need to solve. Lest you think that this blog is alone in its eclecticism, I give you the example of Fred Wilson.