Rollyo is a meta search engine where you can roll your own searches. [i.e. Select which sites are part of your search. You can do this in google manually by adding site:http://your.site.url.com to the search box]
This is similar in concept to Squidoo in that users can act as experts to set up metasets of information.
I think these kinds of tools are useful for finding relevant information and to prevent information overload in the Imersive Information Society which we now find ourselves in.
I will definitely be using its services.