Disabling Spotlight in Snow Leopard is pretty easy, launch the Terminal and type the following command:
sudo mdutil -a -i off
This tells the Spotlight manager to disable all indexing on all volumes, the command will require your administrative password to execute.
Re-enabling Spotlight in Mac OS X 10.6 Snow Leopard is just as easy, just reverse the command to:
sudo mdutil -a -i on
Now Spotlight indexing will be back on and work as usual.