[YokoZar]

A fun hack I remember was that Windows internally used two left-to-right control characters in a window title as an indicator that the entire window should have its content flipped right to left, images and all (imagine a clock animation running counter-clockwise).

This meant that if you could control the window title somehow you could create some surprising behavior, such as putting both those characters at the beginning of a post on a web forum and then having both the web page and browser look backward after someone opened the link.

I believe most things filter for this now, of course.