+1 for hosted LDAP as a service (maybe even backed by GApps).

New startups typically tend to go with Google Apps for their email needs. Google exposes authentication via OAuth2. However many services (specifically developer tools such as gerrit, jenkins) do not support OAuth2 yet (only OpenID, which sadly Google deprecated some time ago) and LDAP. Having an LDAP frontend to provide identity/auth so that startups can use a single set of credentials across their internal applications would be nice.

TL;DR - LDAP frontend to Google identities would be nice. From when I last checked (few months ago), no one offers this.