If you mean you want a local copy of your content and settings, you'll have to export the MySQL database from your server to a file and then do an import on your MAMP setup.
You're probably better off just using sample content locally, using something like this or this.
If you're working on your theme, everything should be contained within wp-content/themes/theme_name
and that's the only thing you really want to be transferring between your local and remote installs.
If your query is really about editing content (posts and pages), then I would recommend Marsedit. You can set it up to show you previews in your blog's style unless your formatting relies on plugins.