http://www.browserleaks.com/canvas http://www.techopedia.com/definition/27310/super-cookie https://panopticlick.eff.org/
Every 3rd party HTTP request can already be used to track you -- being logged into a social account just makes the tracking way easier for them.
The prominent example to trigger a 3rd party request is the 1px GIF. Incognito mode won’t help you in this case.