I've looked over Rollyo and I guess there are ways it could be useful, but frankly, I'm not very impressed. The best possible use I could come up with for it didn't work. I was really hoping to be able to search both my school library catalog and our public library catalog at the same time but that didn't work. I would love if I could make it search multiple databases we subscribe to, but it doesn't seem to work for that either. I don't like that there are a bunch of advertisements in the results list: things like Google's search at least keeps sponsored links separate from the true results.
I even tried searching through other participants' blogs in hopes of finding someone who used it and liked it so I could figure out why I should like it too, but I didn't really find much positive feedback on it that way either. If you can tell me why you like it, please share!