Yoono is a social-bookmarking add-on for Firefox (and IE) which is similar to the popular StumbleUpon. It works on the premise of sharing your bookmarks with other Yoono users. When you first install and configure Yoono you are prompted to create an account and also select which of your bookmarks you would like to share. Never fear, you can also specify which bookmarks are private and should not be shared (like ChiaPetFansite.com).

What I like about Yoono is that it takes the work out of social bookmarking. It doesn't take a rocket scientist to use Del.icio.us or Ma.gnolia (or any other social bookmarking site) but since it works with your existing bookmarks it makes the 'social' aspect completely transparent, almost a brainless activity. Depending on your personality, this can be a pro or a con. While you're viewing any particular page, a ticker is displayed below the location bar which suggests similar sites to the one you're visiting. The only problem I had with this feature is that it would show links to the home pages of search sites or social news sites (like google.com or digg.com), which doesn't hold a lot of value for me. Since I can only presume this is based on other people's bookmarking habits, I'll give them the benefit of the doubt. It would be nice if it would show only links to actual content. It does also feature bookmark syncing, a la Foxmarks, which I think most people will find useful. Overall I think it's a really fun add-on that is worth checking out.