People who have or had a valid CRSid (the familiar name for Cambridge University Computing Service's Common Registration ID system) are entitled to have a people.ucam.org URL to point at their currently preferred set of webpages. This URL may be updated from time to time such that it provides a a permanent address for webpages whose actual location may be forced to change.
As an example:
http://people.ucam.org/~adw27/
points to
http://www.chiark.greenend.org.uk/~andreww/
people.ucam.org is a new service, and should be considered experimental for a few months. It is currently hosted and managed by the SRCF, though it is expected that the hostmaster of ucam.org and the SRCF will ultimately appoint a separate maintainer.