I have been playing with Rollyo for a little while now and love it. This tool allows you to focus your search down to a maximum of 25 web sites and search within the content of those sites for whatever you would like. A great asset when you don't need a Google or there isn't a search engine for the task that you are doing.
Basically, you create "Searchrolls" which can be tagged and then shared with other users. There are a couple of great tools like a desktop widget, firefox search extension, importing bookmarks from your browser, and site search for your web site that you can include your searchrolls in. The site search is powered by Yahoo.
Here is a searchroll I created for free stock photos. http://rollyo.com/qdsouza/free_photo_search/