LiveLines is an extension for the Firefox browswer that places an icon at the bottom of your browser window. Click on the icon and you can add the current website or blog you're visiting to your Bloglines feeds.
Here on the del.icio.us site you can choose from several bookmarklets that you can install (versions for Explorer, Firefox, and Safari) in the bookmarks bar of your browser. Click on the bookmark and you can add the current website or blog you're visiting to your del.icio.us bookmarks.