Mendeley - active on-line bibliography

Have just installed Mendeley, on-line tool from the creators of Last.fm which, similarly, allows you to create and organise a personal library of the papers you use on-line, see what are the 'favourite' papers within a discipline (and follow/shape those trends), share libraries with others, annotate and tag your papers, import them as references directly into documents you are producing etc. Can see it being a brilliant teaching and research tool, with implications for how research is disseminated (and long term for traditional measures of research impact, such as citations). As of 11 September the tool had 4 million references in its database. Sounds big, and it's currently doubling in size every eight weeks (listen to Vic Keegan's interview with founders Jan Reichelt and Victor Henning).

My first difficulty with it was having to select a discipline to tag myself with (it was ever thus). Opted for psychology and will see how that works out.

Later: Having browsed Mendeley, find its largest user groups (of a community of roughly 25,00 users) are biological scientists and, not surprisingly, computer and information scientists (psychologists have a respectable presence; designers, a select few). Find that, at this stage of its development, the temptation is to look at the 'most read' articles, the first of which Defrosting the digital library is an excellent introduction to the challenges and opportunities facing Mendeley and its competitors. The last thing I'd be likely to be doing on Last.fm would be listening to the most listened to track.