Use Gmail's Multiple Inboxes Feature to Manage Multiple Addresses

Stacking together a handful of separate features in Gmail gives you a unified inbox for managing multiple email accounts, and an easy way to glance at and manage them all.

Earlier this month a feature appeared in Gmail Labs: multiple inboxes based on labels. Zach Gellar, over at The Official Gmail Blog, has a great tip for leveraging the multiple-inbox trick into a full fledged control panel for multiple email accounts:

1. Turn on Multiple Inboxes from the Labs tab under Settings.
2. Set up a filter to auto-archive all mail sent to your work or school address.
3. Customize one of your multiple inboxes to show mail sent to your other address. To do this, go to the Multiple Inboxes tab under Settings and set up one of the panes to search for mail sent to your other address.
4. (Optional) Use a "custom from" address so that replies will be sent from Gmail but as if they're from your other account. This way, your coworkers or classmates won't know the difference.

Once you've set your email to be forwarded and properly labeled, you can use the other inboxes not as subdivisions of your primary Gmail account, but as inboxes for separate email accounts. Genius! While some prefer to keep their various email accounts compartmentalized, if you're not opposed to creating a mega-inbox, this trick stands to greatly cut down on the time you spend navigating to, and taming, your email.

Source: Official Gmail Blog and Lifehacker