Also see here: http://ez.no/doc_hidden/ez_publish/technical_manual/4_x/reference/configuration_files/site_ini/sitesettings/sitelist
Those SiteAccesses mentioned in site.ini are listed in the webdav-context after login. But i don't think there is a way to list only the sites you are allowed to read/write to. But better than nothing.
Also be informed, that this list is referenced in the admin-interface for package-import/export stuff and i think linking groups/users permissions to different sites too. So clearing or minimizing the list also affects the admin-interfaces behaviour.