Diigo is a versatile internet-based tool that is great for small group research and collaboration.

In a nutshell, Diigo is:

1) A social bookmarking tool, allowing its members to bookmark sites, tag them with keywords, and then network with other people and share their sites.

2) An annotation tool.  This means you can highlight text and add annotated stickynotes, right on the page.  Then you have the ability to share that information with other friends, members of your small group, or anyone using Diigo.  Not only can you then see their highlights and stickynotes, but you can comment on each other's stickynotes.

3) An online community, in the form of a Diigo group.  Instead of having a discussion in a forum, however, the discussions take place right on web pages.

The video below gives you a taste of all the things Diigo can do.

To get started, first create an account at the Diigo site.  Here is a tutorial on how to create an account.

Then, you will want to install the Diigo toolbar so that you can easily highlight, annotate, and bookmark sites.  Here is a tutorial on installing the toolbar.