I had one page named "Spark" and it had a child named "Spark Syntax" on this blog: http://blinks.wordpress.com/
I deleted the Spark Syntax page (from the edit screen), but the link was still on the sidebar. I then cleared my cache, but still there. I then created a new one with the same name and deleted it from the manage pages screen, same result.
Might be a problem with caching on the server, or with some proxy that I don't know about, but I've never had a caching problem before.