Firefox 3 lets you tag your bookmarks, but it doesn't give you a outstanding way to browse your bookmarks by their tags. TagSifter tries to. Select a group of tags in the sidebar or menu, and TagSifter shows you all the related tags and bookmarks. Or search your bookmarks with set operators, like 'tag1 - (tag2 + !tag3)'. Comes with a software to help tag your existing bookmarks as you move to Firefox 3.

The license of this software is Free Trial Software, you can free download and get a free trial before you buy. If you want to get a full or nolimited version of TagSifter, you can buy this browser plug-ins software software.