An Interesting Virtual Keyboard

While Apple's Keyboard Viewer can be quite useful, it lacks some capabilities one expects in a true virtual keyboard, since clicking the mouse on Shift, Option/Alt, and other modifier keys does not have any effect on input -- to create uppercase or accented characters you still need to use the physical keyboard. 3rd party alternatives have been very costly, but I recently found a cheaper one which may meet the needs of some people: VirtualKeyboard

Among other features, this keyboard can be varied in size and transparency, and can also be used with at least some non-US keyboard layouts.