preferred way of documenting "Sign in With" Providers that are not currently supported?

Thanks for your reply. Tags are a decent idea. I was wondering if there is a way to just enter an item as a login, but with no password field. For example, if you wanted to document that you signed up to a website with a given e-mail address but you don't have an account on the site.

I know you can leave the password field blank but I don't like the behavior where it offers to auto-fill on a site where there is no password. Is there another item type that might be more appropriate than a new login?