To get started, just sign up for free at diigo.com and log in. You can import bookmarks en masse from Firefox, Internet Explorer, or Del.icio.us or add new bookmarks individually at the Diigo site. We like that Diigo can add new bookmarks and tags simultaneously to Del.icio.us, Yahoo My Web, and elsewhere.
Diigo's plain text interface is as simple as that of Del.icio.us, yet with additional functionality. For instance, Diigo lets you select a bunch of bookmarks at once and change their settings; Del.icio.us does not. Unfortunately, Diigo can't preview saved pages within the same pane the way Windows Live Favorites does.

You can use either the Diigo toolbar or bookmarklets, a tiny bookmark applet, to save annotated Web pages without interrupting your Web surfing. If you install the toolbar for either Internet Explorer, Firefox, or the Flock beta browser, whenever you right-click the mouse or highlight something on a Web page, a menu pops up with options to bookmark, forward, search for, or blog about selected content. The toolbar drop-down menu scours four major search engines, as well as within blogs, mapping, news, music, TV, shopping, and reference engines. Choose the Diigo toolbar's Options menu to set privacy preferences.
However, if you already have installed other toolbars, such as Windows Live, Yahoo, or Google, you should toss the ones you don't use. If you find the Diigo toolbar distracting, just skip that download and instead use the Diigo bookmarklet for quick bookmarking. Or, pick the Diigolet to bookmark, highlight, add Sticky Notes, and forward pages to other users.
Let's say you save a recipe for jambalaya but want to add your own secret ingredients. You can highlight, say, step 2 of the recipe and add a Sticky Note describing your own step 2B. The Sticky Notes mini-window appears whenever you roll over the highlighted text on that Web page. Add a Comment instead, and that will show up within your list of bookmarks on Diigo. You can make these annotations private or public to allow comments from other users and cluster a bunch of bookmarks within an album to manage various projects--and export them as a feed. And if you blog, you can highlight text on a site and use the Diigto Toolbar to make a quick post to a WordPress, Blogger, LiveJournal, TypePad, Movable Type, or Windows Live Spaces account.

How can you find the good stuff in your bundle of bookmarks? Diigo's advanced search lets you scour the text of pages you've bookmarked--not just the basic titles, tags, and URLs that Del.icio.us goes through--as well as your own highlights and comments. So if you forgot to tag that jambalaya recipe, a Diigo search for "shrimp" should do the trick. And your tag cloud, à la Del.ico.us, shows the most-used topics. As with Del.icio.us, click any tag to see bookmarks that you and other users have made. At this point, many popular Web sites haven't been bookmarked by many Diigo users. Still, Del.icio.us users are migrating to Diigo; one of its most popular tags is imported:del.icio.us.
As with other services, it's too bad Diigo doesn't offer a way to cull duplicate tags, such as "recycle," "recycled," and "recycling," although you can manually merge them. If you haven't conscientiously tagged your content over time, you'll still have to clean up a mess--but we haven't yet found a bookmarking tool that's solved this problem. And we wish Diigo would autofill as we typed our search query.
Unfortunately, Diigo isn't a finished product, and we ran into glitches. Once you do a search on, say, "hybrid," you're supposed to be able to click Diigo's Subscribe link to get updates whenever someone adds the "hybrid" tag to some content. Unfortunately, this button was disabled during our tests, as new subscription features were under construction. Also, Firefox crashed when we tried to forward a highlighted Web page. Other times, the same action worked without a problem.
Diigo's help includes user forums as well as tips and a no-nonsense flash tutorial. We found the feature descriptions helpful, but we couldn't find any way to contact the vendor for questions.
Judging by common bookmark tags, such as "Web 2.0," the Diigo community is full of tech-savvy users. Still, we find it straightforward enough that a dedicated bookmarking newbie shouldn't have a problem adopting Diigo as a research companion. Diigo is great for taking notes on Web pages and using them to collaborate with other users--and since we started using Diigo, we've lost our appetite for Del.icio.us.