The Rollyo is great for narrowing searches to only those sites that have relevant information. I looked at the Rollyo search rolls mentioned in the instructions and had good results from the searches.
I searched for Hamlet in the public domain e-books Rollyo and the rare books Rollyo. Both yielded good results. For the e-books, I think I would be tempted to go straight to Project Gutenburg to search for a book, but the Rollyo does search some sites that I was not aware of. Using the Rollyo might yield better results.
A recently added search roll that I used is Crafty Girl Sites. This search roll worked very well in identifying information about felting. In using Rollyo, I was a bit put off by the advertisements. I had to read the information carefully to make sure that I was not sellecting a link to an advertiser.
I created a Rollyo search roll for library news. I tried it out for information on wikis, and it worked like a charm. A very useful tool. It took a few tries to get it posted to my blog, but I finally pasted the code into the right place. No question that this is a great tool for anyone doing specific research on the web.