Another one similar to Livebinders is Jog The Web. I know there is an extension for Firefox that goes with it. One nice thing it does is allow you to annotate a bit above the frame for the site, which can be helpful, though maybe more for use by a class than as a bookmarking tool.
Livebinders also allows layouts so you can annotate. I agree with you Jeff, I regard Livebinders and Jog the Web as good ways to group a smallish number of resources to share with other people.
As a central place for all my bookmarking needs (I have getting on for 2000 bookmarks!) I would not use those. Checking some of my Diigo lists this morning I was reminded that Diigo's webslides provide a nice way to present sites. See this for example - a Maths Challenge list.
I received an email today warning of the end of delicious and suggesting that I backup my delicious links. Not sure how true this is.
This news was all over the place the last couple of days, there is a link here somewhere. Yahoo will not be working with Delicious anymore. In the Delicious blog they say they are looking at options.
It is very simple to get all your Delicious bookmarks into Diigo. Backup is always good! How to do it here.
My reason for always automatically sending my Diigo bookmarks to Delicious is just that - more secure to have them in two places!
Just to add to the news - future for Delicious does not look promising - see Mashable.
The Web2.0ERC European Union funded education project has produced a video "How to - Guide No 2-Social Bookmarking" you can view it at:
Our Facebook group (also a Community of Practice' that you can contribute to): http://www.facebook.com/pages/Web-20-ERC/317534459957
The video looks interesting but Delicious seems an unfortunate example to use.
Its future looks uncertain.