HOW TO HAVE MULTIPLE INBOXES IN GMAIL

Google on thursday introduced the multi inbox feature through its gmail labs feature.The new feature--called Multiple Inboxes--allows users to have multiple viewing panes open simultaneously without having to open another browser window. The upgrade gives users a quick view at important labels as well as saved searches

How to enable this feature
You can get started simply by clicking the tiny green icon located right beside the Gmail settings link. Once Multiple Inboxes is selected, there will be several additional panes hanging out beside your main Gmail window where you are free to adjust what you want to view on those areas simply be clicking on the settings link
Read official gmailblog post