A couple of great videos via Zbigniew
Avi Bryant's powerful spreadsheet editor that remembers changes that you make by hand and can apply them in bulk to the rest of the lines in your spreadsheet. Note that Avi's a Smalltalk guy, and a more primitive version of this (repeat last replace) has been in the Smalltalk environment for decades. Cool to see that Smalltalk ideas are still proving revolutionary 30 years later :-) (And cool of Avi to keep discovering them and taking them further)
Another way of doing something similar : Mass Edit which puts simultaneous editing cursors under the user's command. Very clever. That's from a video by David Huynh who seems to be involved in a lot of other neat research, like this mashup tool.