The profile selector lets you know which account you are currently signed in to on a particular browser tab. This is necessary to distinguish accounts when you have multiple accounts for a particular service set up (for example, more than one Twitter account). You can use it to toggle between accounts within a particular browser tab. Select Home to load the homepage for the selected service and log in to the selected account. Select switch to to reload the page you are currently viewing with a particular account - this can be used, for example, on websites with Facebook connect support to log you in automatically.