del.icio.us is a social bookmarking tool used to store your bookmarks online, so you can access them from anywhere.
And there are 2 ways to integrate del.icio.us into your blog too. Linkrolls are a way for you to have your latest del.icio.us bookmarks displayed as part of your website. You can style the css to blend in and adopt the look of your site, especially in weblog sidebars. You can decide the number of item, tags, icons, bullets and best of all decide which tag to show. This allows you to customise a particular tag for use on your blog only.
Tagrolls are a new feature are a way for you to display your del.icio.us tags as part of your website. You can customise the size and colors of the tags and arrange them as a cloud or list with counts. This is useful if you are using del.icio.us tags to create categories in Blogger.