XCopy

Very basic extension (50 lines of code) to allow Unix-style copy and paste: select text to copy to an auxilliary clipboard and press the middle mouse button to paste (at the mouse cursor location). Very addictive and dangerous, like all good things.

Note: this is an additional copy and paste mechanism, the windows clipboard is never touched. And 
in my experience, this is what makes this infinitely better than thinks like AutoHotKey scripts which use the windows clipboard (of course, the drawback is that it's not system-wide).

No configuration, obviously the source code is dead simple and can be modified to change the behavior (e.g. pasting at the current caret location instead of the cursor location).