Erik let me know about two other 'sites which reference back to content on "this day X years ago". puce.com is a personal page going for at least five years by someone younger than me. Bah. (I wonder what would have happened if I'd discovered personal content originally, instead of trying to build magazines and do great design (I failed in both)). And... spacegirl.com has painfully excellent design sense and utterly brilliant content. I like especially the journal from 1989 (1989!) with current day comments.
These references back to content past tie in interestingly with an off-hand comment I'll make in two days time about the lack of interaction with history on the internet.