Couldn't find it for the life of me. Gave up trying to find an answer, said "screw it", and just started using alt+tab to switch between running programs. Still annoying though.
Incidentally, I discovered if you move your mouse cursor over the title (top) of a window that's open, using mouse's scroll wheel will make you switch between the last two windows.
Happened to be on irc.freenode.net #kubuntu ... and someone there posted a similar problem. To get back your application list in your toolbar / panel:
- right-click on toolbar in an empty spot
- click "Add Applet to Panel" (this is where you say AHHHHHH!)
- click Taskbar and OK.