Associate work email addresses with your Google account
Login to the Google account you want associated with the email address
Under "Personal Settings" find the list of "Email Addresses".
Click "Edit" to change email associations
Add addresses to the " Add an additional email address:" field
A confirmation email will be sent to that address
Click the link in the confirmation email
Once the confirmation has been received by Google you can go back into Personal Settings | Email Addresses and check the Activate box next to the address.
Why is this useful?
Associate email addresses with your account
Adding email addresses helps Google associate useful information with your Google Account. For example, Google Calendar can show invitations sent to any of your addresses.
Find out what accounts an email address is linked to