that copy/paste script reminds me of something that I've always wanted in SI. A bit different but a variation on it: simplified copy-paste keyfunctions in the timeline. So, selecting keyframe(s) and then hitting ctrl-c/x, going to other timeline position and hitting ctrl-v.
It's actually like having dopesheet abilities in the timeline, it speeds up the workflow a lot IMO.
For single keyframes you could even speed this up a whole lot more - just hovering over the timeline with the pointer would be enough to tell SI it's keyframe at current frame you want to handle. So ctrl-x cuts current keyframe, as long as timeline is area of interest.
Does SI recognize area of interest?
I've never done a tool that directly interacts with the timeline, I'll look into it and see if I can come up with something.
This week's tool is a request from a guy from work. A simple tool to quickly offset keys in the timeline.http://philmelancon.wordpress.com/2012/03/06/offset-keys/
Direct link to the script if you don't care about the how-to: http://dl.dropbox.com/u/64117454/pmOffsetKeys.pys
(Right-Click, Save as)