To avoid checking several emails (yahoo, hotmail, gmail etc) Gmail's Mail Fetcher can download messages from up to five other email accounts, centralizing all your email in Gmail. Here's instructions how to set-up Mail Fetcher http://mail.google.com/support/bin/answer.py?answer=21289

OR you can set-up gmail to let automatically forward incoming mail to another address.

Here's how to forward messages automatically:

1. Sign in to Gmail.
2. Click Settings at the top of any Gmail page, and open the Forwarding and POP/IMAP tab.
3. Enter the email address to which you'd like your messages forwarded.
4. Select the action you'd like your messages to take from the drop-down menu. Choose to keep Gmail's copy of the message in your inbox.
5. Click Save Changes.