If you have any pdf or word documents in your attachments it can be immediately viewed in google docs rather than downloading and opening with the specific application
If u wanna open emails in new window, just click "new window" found at the top right corner.
The mail composition box can be easily resized for gmail using this firefox addon.
Gmail has colored labels so you can better organize your email. Just click on the color swatch beside each label to assign a color. Colored labels only works with the latest version of Gmail and is currently available for Internet Explorer 7 and Firefox 2.
http://mail.google.com, https://mail.google.com, http://www.gmail.com, https://www.gmail.com, http://gmail.com, https://gmail.com, or http://googlemail.com
or the work place email client can be easily configured to access gmail. Check this link for configuring the email client.
or you can use google desktop to access gmail
If you wish to compose new emails in new windows then hold on "shift" key while you click on "compose mail" button. Care should be taken that the popping out window is not blocked by the browser.
To delete mails quickly select the emails to be deleted and press " shift + 3" and the selected mails would be moved to trash. The same could be done while reading a particular mail.
Access upto five different email accounts using MAIL FETCHER in gmail. For more inputs about mail fetcher check out this link.
Get email alerts on your cellphone. For this your cell phone must support some basic requirements. Check here on how to set up this facility.
Google sync calendar can be used to sync gmail calendar with Microsoft outlook calendar. Know about it more in here.