Okta - Enterprise-grade identity management for all your apps, users & devices
BugMeNot - BugMeNot is a free Internet service that provides usernames and passwords to allow users to bypass the registration process for websites.
Auth0 - Auth0 is a program for people to get authentication and authorization services for their own business use.
OneLogin - On-demand SSO, directory integration, user provisioning and more
OpenID - OpenID is a safe, faster and easier way to log in to web sites.
Atlassian Crowd - Crowd is a single sign-on and user identity solution.