mime types

Hi,

Is it possible to write a hyperlink to a file, so that when it is clicked,
the user is offered weather to open the file or to save it to disk?
I have read something about the mime type: application/octet-stream that can
be used. I know that browser behaviour affects how files are dealt with, but
it would be good to try and 'suggest' this is the way to deal with that
particular file.

Thanks
Nathan