Searchmash is Google's site for experimenting with new features in its core search business.
Visiting Searchmash, you're confronted with a mostly-blank page, with a logo, and a one-line text entry field inviting you to type a search query.
Enter a query and you get a single page that shows search results, with side-panels showing search results in images, blogs, videos, and Wikipedia.
Results are presented in a continuous scroll, according to SearchEngineWatch, but I couldn't get that feature to work. Maybe Google discontinued it since SearchEngineWatch did its analysis last month. Or maybe I just wasn't holding my mouth right when I tried it.
You can also drag-and-drop search results, so if you like result #30, you can move it to the top of your list.
Google is keeping its involvement in the project quiet, according to SearchEngineWatch; they dug and dug and found out Google's sponsorship on the privacy page, but not anywhere else on the site.
In a Q&A with SearchEngineWatch, Google explains: "The site does not include Google branding to help us gather more objective data about user response to new interfaces.... In this case, one of the important factors we wanted to address was the influence that may come from Google branding. " SearchEngineWatch goes on to theorize how write-ups like this one won't mess up Google's results.