Gmail Labs has just launched a new feature to view multiple panes in the same Gmail window. You can setup your labels or searches as a new pane.
If you have setup multiple email accounts with Gmail, and have associated a label for each of those email accounts, this new pane feature helps you view each of the accounts new emails separately in the new panes. I really like this new feature, very useful.
To use this new feature, you have to first enable Gmail Labs for your account (if not done already), then go to Settings -> GMail Labs and enable “Multiple Inboxes” from the list of Labs options. Now you will get “Multiple Inboxes” menu on the Settings pane. You can create up to five different panes by manually entering the code for label or Gmail search options.