This School Library Journal article, Best of Social Bookmarking Article, was one I'd saved from a while back for when del.iciou.us came up. It mentions Diigo and the author of the article says it his favorite social bookmarking tool. Because of that, I thought I'd take a look.
Diigo is very similar to Del.icio.us, except that is has more features and tool for a researcher. These tools were what appealed to me from the article. Diigo allows one to import bookmarks just like Del.icio.us, so I just imported my bookmarks complete with tags from there to speed things up. There are two ways to have the sticky note and highlighting tools that Diigo offers. You can download an extension for your web browser, which of course, I didn't have the latest and greatest Firefox, so I couldn't. The other way is to create a Diigolet on your bookmarks toolbar (simply a drag and drop) and then you click on it when you are on one of your bookmarked pages and the tools appear in a navigation bar at the top of the screen. I can then add a sticky (post-it) note to anywhere on the page and also highlight text and have it saved for later. Then I can come back to the page and look at what I'd marked up. If only this had been around for my senior undergrad paper... Below is a screenshot from the Republic of Pemberly. (Which btw, is a great JA, site if you need one!) See the yellow sticky note and the yellow highlighting I did? Diigo remembers what you've done on that page in your bookmarks. Kinda cool, eh?
Overall, I liked Diigo. Although, I think Del.icio.us has a more simpler user interface. I also noticed that I was pretty much the only person that had some of the bookmarks I do and on Del.icio.us, I was one of several hundred. I guess that means more people are using Del.icio.us right now. I will have to play with Diigo a bit more but I could see real applications for use in high school and colleges and how students do research.