I'm looking for a sticky notes/knotes/etc type program with one difference: I can stick a note on a window, rather than the desk top, and it will remain attached to the window.Basically, I want to be able to annotate windows. I want to be able to say this xterm is the one where I'm doing project X This application is running test Y this emacs is working on this bug etc. 
sticking stickies to windows
software rec;gui;desktop