a look at some of them.
For instance, an early toolbar design had a taskbar with thumbnails of running programs instead of icons and pop up menus. But the icons were too small to be usable. Another version used a "Bat Signal" because when you scrolled your mouse over an icon the full window would open on the desktop, and a spotlight would shine up from the taskbar at it.
You can find more early ideas for Windows 7 at TechRadar.