TL;DR: I've not been using Delicious as much lately, having been lured away by simpler sharing services. But, I think there's a lot of metadata value in tagging that I'm missing out on.
In case you're new here, this is who I am with respect to this post: I really like del.icio.us and have done a lot of thinking about it. I was an early del.icio.us user in 2003. I posted 10-20 items per day for a good while. I wrote a book about it, and I worked on it at Yahoo! for a couple of years.
But, especially lately, I've been wandering away:
When I left Yahoo!, I felt so-so about what was going to happen to Delicious. So, I whipped up my own clone using Kohana PHP.
Feel free to grab the code, but it's abandonware. I had great plans for it, but I only got as far as the basic features and a plugin to copy posts back to my original del.icio.us account. That scratched my itches: I had my bookmarks self-hosted, I still posted to Delicious, but I didn't feel particularly compelled to promote the project beyond that. At this point, I'd rather not touch PHP for personal projects, so there you are.
But even with my own self-hosted bookmarks, I've dropped off in general. Until about 2 years ago, I was a madman posting around 10-20 bookmarks a day. Since then, I'm down to less than one a day on average.
What happened? Other channels became rewarding, and my sharing habits fragmented. Google Reader released a sharing bookmarklet, so I started using that. More people I know started using Facebook, so that became more attractive. And, even though it kind of annoys me, I sometimes spam links to Twitter when I think they're particularly interesting.
But now that I think about it, I'm missing out. All these sharing services I've started using are one-click, lazy affairs with no particular drive toward tagging. My only intentional input into the process is to point and nod. Consequently, they facilitate sharing much more than search or recall, in that the richness of metadata extracted from me is reduced. Delicious kind of tricked me into doing all three at once, but newer services are more focused on me as a social entity.
The thing about Delicious is that it wasn't meant for socializing. Rather—as I understood it, at least—it was built to exploit both selfish and social mechanics to extract useful work. In this particular case, the goal was producing interesting collections of things on the web. Compare it to Amazon's Mechanical Turk, only with a non-monetary incentive. Since Joshua Schachter and friends have started Tasty Labs, I expect we'll see them take a shot at applying this notion to other problems.
So anyway, where am I going with this? Oh yeah: I'm using Delicious less these days and I think it's to my detriment. Delicious extracted useful work from me, both for myself and others. It's harder to find things again, thanks to missing metadata and the ephemeral nature of sharing on the real-time web. I think there's a place for Delicious, if only for those of us who like to keep track of what we've found on the web and share the results. I suspect that may be a limited, though highly motivated audience.
What's to be done about it? Well, Delicious is still around, for now. Keep using it, and make regular backups. But, I've got some further thoughts to sort out for another post very soon.