I have a OS X Snow Leropard Server running and I want to disable multivewis from Apache. I could add Options -MultiViews to each .htacces file I have, but I guess there must be a global option. Disabling mod_negotiation.so renders all pages useless so this is not the option I'm looking for ..
In /etc/apache2/httpd.conf you should find the section starting <Directory "/Library/WebServer/Documents"> and remove MultiViews from the Options directive there. The same goes for any other paths if your content isn't in that directory.
As an aside, if you're able to edit the server's main config file you should never have to use .htaccess file. Doing so only slows down the server, makes tracing the configuration harder and makes any use of mod_rewrite a brain-rending disaster.