This is where my content will go. It could be an article, a blog post, a page of links, anything that I can have on the web. It can include images, video, sound, whatever.
Within that content I might have identifiable things, like names of people, places, topics. These are the things that I want to link.
The sidebars will hold the information I am linking to. In this example, I have a place, "Canada," a name ("Alice Munro"), and at least one topic (say "Women writers", "20th century"). By identifying the name as the name of a person, my "tool" should be set to some action, such as: get intro from Wikipedia. For place, it would generate a map. Topics could come from DBPedia, or they could link to LC topics. Some words could be given definitions, like tundra.
Basically, my tool would give me a way to set up a relatively small number of choices that will allow me to pull useful information onto my page using links. The information could be dynamic or static, depending on my needs and the type of data at the end of the link.
Note: this is a pretty ugly example. I suggest looking at the Open Agris implementation for a better-looking interface. What I'm wanting to convey here is not how it will look (because it should be able to look however one wishes it), but how tools embedded in web products could help content providers make links.