Search the future-not black magic

No this is not black magic, it is the wonder of feed powered search. Rather than indexing the sites, the feed is indexed. With the "search the future" feature of bloglines you can get feeds for a keyword you subscribe to.

you can subscribe for the same at the following url, but you need to have a blog lines account for that.

http://www.bloglines.com/sub?mode=3

In their own words -"Want to know when someone posts something you're interested in? Enter a search query below, and be instantly notified when a blog entry that matches it becomes available to you"

This apart it would be useful to get alerts when somebody starts using a new word. The service should filter out typo's and show only folksonomies. (Words created due to a need for that word)