Type in a URL on the Xmarks site (there’s a preview here) or click the link that the Xmarks plugin puts in your location bar to see how frequently the page you are visiting is bookmarked, how highly it’s rated, and what sites Xmarks thinks are similar. That’s based on what other sites people bookmark in the same folder. A lot of people put bookmarks for Mint.com and Wesabe.com in a folder called Finance, so they show up as related sites and Xmarks tags them with the finance category. You can click through to find sites in a specific category once you've done a search, but you can’t simply browse by category. The Xmarks plugin (which is available for Firefox now and for IE and Safari in the future) also adds icons to Google searches to mark the three most popular results. Click the icon to get the same ratings and similar site suggestions. Because they’re based on bookmarks, the results in Xmarks tend to go to canonical sites rather than news stories. Everything in the social networking category is a link to a site like Facebook or Bebo, and similarly, sites that get highlighted in Google tend to be official and generic sites. This makes Xmarks as much a reputation service as a search tool.