OK, a few things I just want to gripe about: the person speaking over the top of the Del.ciou.us tutorial has this sharp "s" sound in her voice, the kind of thing that happens to many people with dentures, and it annoyed me quite a bit. It might have something to do with the equipment being used to record, as a few times, particularly with "p" sounds, there are small blasts of distortion, and the whole overall sound is a bit harsh. Not the best tone for educational listening, or any listening really. Moving on...
Del.icio.us makes me think of LibraryThing for researchers. But it doesn't have that zip that I'm looking for. Wading through all these tools just becomes tiring after a while, particularly after I've used some technology that is extremely user-friendly (e.g. iPhone, iPod). For example, one of the new technologies that I want to learn is podcasting. I clicked on the tag "podcast" and selected the popular tab. I wasn't impressed with what I found. Very simplistic posts, like the kind of thing about nutrition you'll find on Yahoo news links throughout the day. If I want to learn about podcasting, I'll pursue it myself, through basic online searching, or through the traditional library means.
Researchers could definitely use this tool. But I don't see how the bookmark feature on your computer is any worse than Del.icio.us. You lose the social networking aspect of Del.icio.us, but I wonder if that's any loss. I'm glad that I've introduced Del.icio.us to myself, in case I talk to someone in a library situation about it, but I'm not really excited about it for myself.
8 years ago