how to change default open application

[Raul Acevedo <raul cantara com>]

How do I change what application Nautilus uses by default to open a
given document type?

I though there was some application to change this, but I can't find it.
I also thought that if you say "Open with Other Application", whatever
you select becomes the new default, but that's not happening.

Thoughts?

Raul