Renice (blog, links) introduced me to del.icio.us today. It's a "social bookmark" site. At first I didn't get it. I looked at her links and I didn't get the appeal. And the layout looked sort of lame, frankly. I already use a9.com to store my bookmarks server-side, so why switch?
Then took a longer look...and I got it. When you create a link there, you give it a bunch of "tags." A single link can (should?) have multiple tags. Unlike a traditional hierarchy of folders where a link lives in just one spot, tagging allows you multiple paths to a single bookmark.
It doesn't end there. The URLs are human readable, and you can perform intersections on tag sets. For example: to see every link that I've tagged "friend," you can go to http://del.icio.us/pettijohn/friend. To see every link that I've tagged "blog," visit http://del.icio.us/pettijohn/blog. To see the intersection of the two sets, which is to say links that are tagged with both "friend" and "blog," go to http://del.icio.us/pettijohn/friend+blog. Pretty cool, eh?
There's also a social aspect to it. Bookmarks you post there are public (obviously), and it's interesting to explore the Internet through other people's bookmarks. You can do things like visit http://del.icio.us/tag/csharp to see bookmarks that everyone has tagged as "csharp" (I chose to write it out since # is a special character in a URL). Then you can find a link created by someone else and click on the "csharp" tag underneath it to see everything that that individual has tagged "csharp." Then see what other categories that person has tagged other links in that category...and explore! You can also click the "and x other people" linkwho else has the same page bookmarked.
There are RSS feeds available for every tag (http://del.icio.us/rss/pettijohn/blog+friend, for example). You could create dynamic lists of links on your blog with something like that.
I have two concerns, maybe just one, really: the lack of a hierarchy was a concern, but then I came to understand the set intersection which can accomplish the same thing. The other concern, the real concern: how is del.icio.us funded? There are no ads and no fees. I don't know how it can sustain itself. It's funny: if it had Google text ads, I would be much more comfortable with the service. I don't want to see it go away, and I don't really want to pay for it, either.
I'll be switching from a9.com for my server-side bookmark management. a9 is perfectly functional, and it introduced me to the freedom of storing bookmarks server-side. Del.icio.us, however, offers a unique and cool way to store, share and browse bookmarks that is unlike anything else I've seen.