if youre talking about capx files, they're generally saved on dropbox.com or other file sharing site.
theres also the arcade you can link to
i havent dabbled much with outside publishers, but theres always sites like newgrounds, albinoblacksheep, etc, where you can submit games to be hosted. if you're just trying to show a tutorial, you could even take a screenshot and host it that way through photobucket or imgur etc. shit, even facebook, and then just post the pictures url.
however, if youre just looking to show people stuff, easily and free, id say to host the game itself use scirra arcade, and to host the c3p or c2p file, use drop box