Ten years ago or more we had several blog-specific search engines and services: Technorati, BlogBridge, and others.
One of the great things about these services was not just being able to search for something but being able to set up persistent searches: that is, you’d get a search as an RSS feed, and in your feed reader you’d get results from all over the place on the thing you’re searching for.
In the obvious and common cases, you’d set up searches for people linking to your blog, writing about the apps you work on, mentioning the place where you work, and mentioning you.
Doesn’t Superfeedr fit that bill today?
Also, I miss referer logs.