Inspired by a presentation at Hypertext '04, Matt Webb mashes up del.icio.us, Blogger, and Technorati, in a brilliant loosely coupled scheme. The gambit would allow people to easily and freely tag links, ala del.icio.us, in their weblogs. A de facto standard attribute on a tags (maybe img too?) could carry the tags. Then Technorati, since it does the hard work of crawling all those blogs anyway, could stand in for del.icio.us: generating a front page of recently posted links or creating per tag webfeeds. Heck, they could even provide whizzier search than del.icio.us.
Minor note, Webb didn't actually toss Blogger in the mix. I just used it as a proxy for weblog authoring tools. Continuing in that vein, personally I'd throw Waypath at the task before Technorati. 7 days worth of del.icio.us isn' t all that useful.
Honestly, this scheme is just simple and useful enough to catch on. What it needs is a littlte fine tuning (e.g. what's the simplest, cleanest way to add metadata to links) and some evangelism in the form of "here's how to do it in your weblog tool," preferably with an easy to install plug-in. Knock out LiveJournal, MovableType, WordPress, TypePad, and some Java based blog tool, and you're probably 90% of the way home.
It's so crazy it could work!! At least until the tag spammers show up.