Restarting the Mac OS X Dock, Finder, Spaces or Menubar

Sometimes it just seems to happen, you're getting the spinning beachball on Mac OS X System Applications/Tools, like the Finder when connecting to a messed up network share. Luckily, most of the time it's easy (yet annoying) to fix via starting the Terminal and using following commands (beware, the names of the programs to kill are case sensitive!):

The Finder crashed:
killall -KILL Finder
(you can also restart the Finder by option (=alt) + rightclicking the Finder icon in the Dock and selecting Relaunch. It doesn't always work though.)

The Dock crashed:
killall -KILL Dock

Spaces crashed:
killall -KILL Dock

The Menubar crashed/refuses to be clickable:
killall -KILL SystemUIServer

All these services should automatically restart after they have been killed. If for some reason they won't, you're probably better off just rebooting (to be sure, the "Shut Down" option from the Finder/Menu bar will probably not help, just go to the Terminal and type: sudo shutdown -r now - provide your Admin password and your machine should be restarting).