I note that several participants in the Learning 2.0 programme at Imperial have
mentioned that dealing with all the additional accounts they are
creating as they take part in the course (so far, MSN/Windows Live,
Wordpress, Wetpaint, Bloglines or Google Reader)

Where services are offered by the Imperial ICT
service one advantage is that they usually integrate with the standard Imperial
username and password – so you only have to remember one login. It may
also be worth mentioning that Wetpaint supports a login method called ‘OpenID‘
which is a way of using a single username/password (owned by the user,
not by the service they are logging in to), to access many sites. In
theory it is a great idea, although in practice it isn’t always as easy
to use as you might wish (see http://electronicmuseum.org.uk/2008/07/16/openid-fail/ for a critique of OpenID)