Just saw this over at design blog BittBox: when drawing with the Shape tools in Illustrator (rectangle, circle etc.), holding the tilde key (the squiggle key to the left of the 1 key on U.S. keyboards) and then dragging the mouse will result in lots of duplicates of the shape following the trail of your mouse pointer.

Can’t think of much use I would have for it, but I thought I would throw it out there.

via BittBox