You can put anything you like in the email field. I use fake addresses such as tom@tmbp (me on my laptop), tom@tw7 (me on my Windows 7 PC), and so on. Add thes

You can put anything you like in the email field. I use fake addresses such as tom@tmbp (me on my laptop), tom@tw7 (me on my Windows 7 PC), and so on. Add these addresses to your email addresses list on the settings page of your github account if you want your github avatar, etc., to be shown against commits using these addresses.