You can view your GitHub notifications from any GitHub page. Clicking the notifications icon will produce a dropdown. (You can still click the link at the bottom to get to the full notifications page.)
Repositories can be collapsed by clicking their header.
Notifications can be marked as read in the normal way. (Note this only applies to those visible notifications for each repository.)
(Optional) Can makes files in diff views collapsible.
(Optional) Can change the colour of the notification dot.