All four of these tools try to make sense of the mass of information on the Web. Xmarks tells you what matters to other people, as long as you know a Website to start with. At the moment, that tends to be top-level pages, so perhaps Xmarks is most useful for checking which big-name sites are actually worth looking at. You could also use Xmarks to check which are legitimate.

If you want to track down information about a specific person or company, Evri is a quick way to do it. Although it’s the most advanced of the four tools, it still doesn’t have quite everything you want to know about and it doesn’t handle more abstract concepts.

But Primal Fusion is all about abstract concepts, and when the service eventually becomes more robust and handles more sources, it will be a very interesting way to explore ideas.

Ensembli has to learn about you, so you need to use it as a way of following topics in which you have an ongoing interest. Once it knows you, a new search will be more relevant to start with–as long as you think about it in the same way you think about those existing interests. It is an investment.

These brand new tools are helping us towards the holy grail of the semantic Web, if you think of semantic web as stuff that helps you find better results (the original definition was about having Websites make sense to computers so they can work more efficiently on your behalf). But all these tools need to develop much more before they become truly useful.