Google is now presenting the Official Gmail Themes.
“We wanted to go beyond simple color customization, so out of the 30 odd themes we’re launching today, there’s a shiny theme with chrome styling, another one that turns your inbox into a retro notepad, nature themes that change scenery over time, weather driven themes that can rain on your mailbox, and fun characters to keep you in good company,” mentions Gmail’s blog.
Now you can use voice and video capabilities in your Gmail chat. From within Gmail, you can have an actual conversation with someone (seriously, out loud), or even chat face to face over video.
Nowadays, many people maintain separate email accounts for work, for family and friends, to post into forums, and so on. I use several Gmail accounts, and I find it a challenge to read all those accounts without having to set up a POP client or disconnecting and connecting to the Gmail Web site with a browser over and over again.
Gmail Manager is an Firefox extension that can solve your problem. With it, you can manage multiple accounts and be notified as soon as you receive a new message in any of them.
Many people asked me if there was a quick way to get around the firewall that keeps them from being able to access his Gmail at work.
Gmail is Google’s free webmail service. It comes with built-in Google search technology and over 2,600 megabytes of storage (and growing every day). You can keep all your important messages, files and pictures forever, use search to quickly and easily find anything you’re looking for, and make sense of it all with a new way of viewing messages as part of conversations.
Here some way you can access gmail behind firewall.
Instead of using http://mail.google.com use https://mail.google.comYou can also try
GMail Drive is a Shell Namespace Extension that creates a virtual filesystem around your Google Gmail account, allowing you to use Gmail as a storage medium. 
GMail Drive creates a virtual filesystem on top of your Google Gmail account and enables you to save and retrieve files stored on your Gmail account directly from inside Windows Explorer. GMail Drive literally adds a new drive to your computer under the My Computer folder, where you can create new folders, copy and drag’n'drop files to.
Ever since Google started to offer users a Gmail e-mail account, which includes storage space of 2000 megabytes, you have had plenty of storage space but not a lot to fill it up with. With GMail Drive you can easily copy files to your Gmail account and retrieve them again.
When you create a new file using GMail Drive, it generates an e-mail and posts it to your account. The e-mail appears in your normal Inbox folder, and the file is attached as an e-mail attachment. GMail Drive periodically checks your mail account (using the Gmail search function) to see if new files have arrived and to rebuild the directory structures. But basically GMail Drive acts as any other hard-drive installed on your computer.
You can copy files to and from the GMail Drive folder simply by using drag’n'drop like you’re used to with the normal Explorer folders.
Because the Gmail files will clutter up your Inbox folder, you may wish to create a filter in Gmail to automatically move the files (prefixed with the GMAILFS letters in the subject) to your archived mail folder.
Please note that GMail Drive is still an experimental tool. There’s still a number of limitations of the file-system (such as total filename size must be less than 65 characters). Since the tool hooks up with the free Gmail Service provided by Google, changes in the Gmail system may break the tool’s ability to function. I cannot guarantee that files stored in this manner will be accessible in the future.
GMail Drive v1.0.11 - download site #1 (Softpedia)
GMail Drive v1.0.11 - download site #2 (Filehippo)
With thanks from viksoe.dk