Any applications for scribbling over other apps?

Factual Questions
#1

I’d like to be able to optionally draw over whatever applications I currently have running (to make notes.) I haven’t been able to find anything via Google, but perhaps one of you all know.

Windows XP
Something free

#2

Here you go. Not free, though.

#3

This one is freeware, though.

#4

Perfect. Thank you.