Did you know that Gmail is capable to integrate several mail accounts? Most of us have separate company and private mail addresses, and usually we need to check them at the same time.
With gmail, you can reach every mail server via POP and SMTP. Apart from having all your mail in one place, you can also benefit from the great accessibility provided by Gmail, eg. the traditional webmail interface, mobile webmail for WAP browsers distributed with cellphones, IMAP and POP protocols for desktop and mobile mail clients, etc. You can even send mail from your integrated mail accounts via any of the above mentioned interfaces of Gmail.
For details, check out the Settings / Accounts tab