This is a really great web application similar to del.icio.us bookmarking. The advantage of Butterfly is that you can actually customize web pages by adding notes, definitions via hyperlinks, and highlights. Because it is web-based, like del.icio.us., you can access the list of modified web pages anywhere simply by signing into your account. This could prove useful for research projects as well as a personal tool for reference librarians. In addition, reference librarians can build up a set of Butterfly pages with annotations and send them to patrons. I will certainly be trying out Butterfly for myself and consider other uses for this application.
Customize Web Pages with Butterfly