"Ok, get this - it's just like Grease Monkey for Firefox... except it's for Eclipse!"
Now this is cool. I found out about Eclipse Monkey through its name being dropped in a group chat on an DP call and decided to research a little. The article I found is rather old but gives a nice description. Further info can be found at eclipse.org/dash which is the container project.
Think of being able to write scripts that affects functionality across Notes applications in Notes 8. Aspect-based programming for Notes. Hmmmm... It makes my mind wander.
Link to eclipsezone.com: Eclipse Monkey - Now That's Cool