LiveBinders allows you to present a number of pages in one browser window. Easy interface allows you to create subject binders that you can share by making public. Again, multiple site links given with one URL. Linking sites to your binder with the toolbar applet that works with Firefox and Google Chrome browsers. I created a Live Binder for the PACTEC TechBootCamp group here:
http://livebinders.com/play/present?id=18125
start.io is a basic bookmarking site - allows the user to share a group of sites quickly with one short URL. An applet exists for Firefox and Google Chrome browsers. My start.io page can be found at http://start.io/altucker