Gmail Labs that should help fill in those gaps: offline Gmail. So even if you're offline, you can open your web browser, go to gmail.com, and get to your mail just like you're used to.
Once you turn on this feature, Gmail uses Gears to download a local cache of your mail. As long as you're connected to the network, that cache is synchronized with Gmail's servers. When you lose your connection, Gmail automatically switches to offline mode, and uses the data stored on your computer's hard drive instead of the information sent across the network.
Offline Gmail is available to everyone who uses Gmail in US or UK English over the next couple of days, so if you don't see it under the Labs tab yet, it should be there soon.
To know more, read here.