Social bookmarking means storing your bookmarks online, tagging them to remember why you wanted to save them and what you might want them for in the future. You can also share them with others who might value your web surfing experiences. And don’t worry — you can always choose to keep some or even all of your bookmarks private if, for some reason, you don’t want to share.

Social bookmarking sites are in many ways the ultimate folksonomies, categorising web content by an open process of tagging. The result is a road map of the web, based on the recommendations of people who have traveled it extensively.

In many ways, the information gathered by social bookmarking services is like the wild, young sibling of the web directories. But now, every web surfer is a potential editor, licensed to categorize and recommend all kinds of web sites.

What to look for
When researching for this article, I registered with and tested over 20 tools for social bookmarking. Some were discarded because of bugs or spam. The remaining were sorted by these criteria:

A decent amount of users is necessary. Otherwise the whole social aspect looses relevance.
The service has to have quite extensive documentation, FAQ and/or help pages, to guide users.
More advanced users will want good import and export possibilities. Import is necessary for bringing old bookmarks from your browser or from another online bookmarking service, export is important for backup copies and to ensure that your bookmarks can go with you to another service if you decide to switch.
A good bookmarking service should have feeds (RSS and/or Atom) of tags or groups of tags.
I would want my bookmarking service to have a blog so I can be kept up to date about new features, bugs, bug fixes and more.
All the top 5 social bookmarking services in this article comply with these criteria, except for Bluedot which doesn’t have an export option. And the winners are…

Furl
LookSmart’s Furl is one of the seniors of social bookmarking and definitely among the most advanced. If you are serious about your online research, this is the tool for you.

Navigating among all of Furl’s features is easy — everything is stored behind four tabs. The tab My Archive displays all of your bookmarks. All the essential tools are kept in a neat little box. It lets you search your own bookmarks, all of Furl or the entire web. Drop-down menus let you sort your bookmarks by tag, by date or both.

The bookmark list has lots of tools that make it easy to move, delete or email bookmarks, and clicking on the Edit tool lets you store and edit all kinds of information. If you are a blogger or a webmaster, code is available that will display your recent Furl entries on your web site.

Furl is among the few services that store a copy of the whole web page when you bookmark it. This can be a very useful tool. Unfortunately, no copies are generated for my imported bookmarks. I also ran into another problem when importing bookmarks from del.icio.us: Bookmarks with more than one tag had their tags melted into one, e.g. a single tag called “google,searchengine_news” in stead of the two tags “google” and “searchengine_news”.

Netvouz
Netvouz is a powerful tool for social bookmarking. You can view and sort your bookmarks in many ways — all bookmarks or new bookmarks, tag list or tag cloud, like many other bookmarking services. You can also sort bookmarks by rating, date or name.

Netvouz is the only bookmarking service that lets you place groups of tags in folders that are displayed high up on the page. You may also add “Hotpicks” — your most frequently used bookmarks — that always are available on the very top. These features are of great help for those of us who are storing hundreds of bookmarks online.

Netvouz also has an automatic link checker that regularly verifies that all your bookmarks are valid and alerts you in case they are not. I haven’t seen this anywhere else.

The only downside is the community part. Nervouz has no support for recommendations, friends or groups like many other social bookmarking services. All that is on offer is “New public links” and “Popular tags” on the front page.

Del.icio.us
Del.icio.us is by far the most popular social bookmarking tool out there. It is not the most powerful, though. I have kept my bookmarks on del.icio.us for some time now and the reason I stay on is the community. The tools for sharing are not very powerful — you can add people to your network and share links with them, and that’s about it. The effect of sharing can be great, though, because of the size of the community.

On del.icio.us you can view your bookmarks as a tag list or a tag cloud. Tags can be sorted alphabetically or by frequency.

Behind the Help link you find tips for advanced searching and navigation and some unofficial tools that can make del.icio.us work for more demanding users. Among the advanced features are network badges, link rolls, and tag rolls that help bloggers and webmasters to display their del.icio.us activities on their own blogs and sites.

There are no very powerful tools for sorting or editing bookmarks. Paradoxically, this might be a reason for del.icio.us’ popularity. It offers just what the average web surfer needs.

Ma.gnolia
Ma.gnolia has the sleekest design of all the social bookmarking services. And even though beauty is generally considered to be skin deep, high quality web design with lots of white space and easy navigation makes me happy. Never underestimate the value of beautiful design.

At Ma.gnolia there are tutorials, a FAQ and even a wiki for support, and if you send a mail to the support team, you get an answer quickly, even at weekends.

With contacts, groups and discussions, there are plenty of ways to share bookmarks both within and outside of Ma.gnolia.

You can search your bookmarks (or the bookmarks of all Ma.gnolia members) or browse them as a tag list or a tag cloud. You can rate your bookmarks, which is convenient, and it is easy to edit single bookmarks or all the bookmarks with a certain tag.

Furl and Ma.gnolia are the only bookmarking services I have come across that save a copy of the web pages you bookmark. There is also a widget that lets you quickly add a link roll of your saved Ma.gnolia bookmarks to your blog or web page.

But if you have many bookmarks with the same tag, it can be difficult to scroll through them in Ma.gnolia. What I miss is a list view where each bookmark takes up no more than a couple of lines and you can choose to view, say, 25, 50 or 75 bookmarks at a time.

Bluedot
Bluedot is the bookmarking tool for the MySpace crowd. The main focus is inviting friends and sharing dots (your annotated bookmarks). You can import contacts from your AOL, Gmail,MSN or Yahoo! account and then invite them to your Bluedot network. You edit your profile with information about your location and interests and add a photo or an avatar if you like. Of these top 5 bookmarking tools only Ma.gnolia has a similar profile option.

You can choose to view your dots as a list (which is not very useful once you have more than 25 bookmarks) or as a list of tags. Each tag is displayed as a stack, showing the name of the tag and the number of dots in it. There are no other sorting options, but there are plenty of options for sharing: You can comment on your own dots or those of others or you can share dots by email, and each dot has a permalink that displays name, rating, comments and more.

I would have liked an option to view more than 10 dots per screen. And is it really necessary with two prominent Google Ads banners on each page displaying dots?

What about the rest?
There are many great bookmarking services out there. These five are my favorites, but I would also recommend Yahoo’s MyWeb which is a quite powerful tool or Blogmarks which is good looking and includes thumbnail previews of your bookmarked pages.

But where’s Google? The Google Bookmarks tool is simply no good compared to these top 5 tools. The design is uncluttered and the service looks deceptively easy to use, but you need to spend a lot of time figuring out how things work. There is no Help link in sight and the help I found searching Google’s help base wasn’t always useful. Google should either start spending some serious money developing this tool or go out and buy one, like Simpy, which is a very decent service with good community features.