Diigo is good if you want to save websites of interest, and then access them from any computer. It does not provide the automatic bibliography of Zotero, but the user could simply save his bookmarks, return to the sites, hit the Zotero button and the problem is quickly solved. Diigo also features a highlighting tool that allows the user to select text from the site and write comments. If the user is logged in to Diigo and returns to the site, the highlights and comments remain. It it also somewhat useful if you want to find websites related to a certain topic that you are interested in. However, finding academic type articles or journal entires in a person's bookmarks is rare.