- Standard HTTP Cookies - Flash Local Shared Objects - Silverlight Isolated Storage - CSS History Knocking - Storing cookies in HTTP ETags (Backend server required) - Storing cookies in Web cache (Backend server required) - HTTP Strict Transport Security (HSTS) Pinning (works in Incognito mode) - window.name caching - Internet Explorer userData storage - HTML5 Session Storage - HTML5 Local Storage - HTML5 Global Storage - HTML5 Database Storage via SQLite - HTML5 Canvas - Cookie values stored in RGB data of auto-generated, force-cached PNG images (Backend server required) - HTML5 IndexedDB - Java JNLP PersistenceService - Java exploit CVE-2013-0422 - Attempts to escape the applet sandbox and write cookie data directly to the user's hard drive.
https://github.com/samyk/evercookie
In short, everything and more can be used for tracking, and that has really killed the party for the many people who have created responsible, useful applications of these browser APIs.