Google Co-op and creating your own vertical search for your site

I'd like to be able to put a Google Co-op search on my site or my blog like I can with the Rollyo Search. With Rollyo I can specify which sites I want my visitor to be able to search and then I can stick a search box on my site. I would like to see similar functionality from Google Co-op. That is the sort of thing that would really kick-start adoption of Google Co-op. It looks like you can put a Google search box on a page -- like the one on here -- but you'll find that on this page a search for "rover" returns a car company web site as the #1 result, which is clearly not relevant. I'd suggest that the search results on this first search be better refined.