Accessing your gmail in offline mode or from your disk is easily achieved with the help of Thunderbird email client. The good part is google offers POP, IMAP both access type for their emails.
There are handful extensions of Thunderbird to manage/sync with google services. Google contacts can be sync with Thunderbird contacts using "Google Contacts" extension and Google Calendar can be synced with the Thunderbird extension Lightning.
Surprisingly I'm still using Windows 7 OS and the configuration below mentioned is done on the MS Windows 7. I'm using Antivirus by Avast Personal edition that has email shield and for gmail configuration you need to tweak that as well.
You can setup the Google Mail, Contact, Calendar using following steps.
1. Download Mozilla Thunderbird Email Client
2. Install Thunderbird
3. Install the above mentioned Calendar & Contact plugins
4. Mail Settings >> Open the avast antivirus main window -> Real time shield -> Mail Shield -> Expert settings -> SSL Accounts ->
Add following entries
imap.googlemail.com IMAP 993 SSL
smtp.googlemail.com SMTP 465 SSL
gmail.com IMAP 993 SSL
5. In Thunderbird imap.gmail.com port 143
Connection security -> None
Authentication method -> Password, transmitted insecurely
6. smtp settings are same as shown in antivirus settings
7. Address settings -> The extension will ask for username/password
8. Calendar -> Along with lightning extension you also need to install extension "Provider for google calendar"
Now just goto google calender and copy the XML address of your calendar from setting menu and paste it in extension setup in Thunderbird! All your calendars will be synchronized!
If you are planning to buy an Google Android Phone, your contacts, email & calendar will be directly synced on the phone with google account. With the help of Thunderbird and its extension you can re-organize the emails, contacts.