Can I add "virtual" page in WordPress?

On my WordPress site, I would like to create "virtual" page. By virtual page I mean the content that I can link to by URL. I'm using Facebook Webhooks and I would like to have a callback URL like this: http://ift.tt/1maY0Um. I'd like it to be done via plugin, without actually adding any page to the database. Is there any way to add a page in WordPress that way?

For now I'm using http://ift.tt/1o3sAkr and checking for isset( $_GET['facebook-webhook'] ) in the init action. I would love to have it without the ? though.

via Chebli Mohamed