How to Access Gmail When It's Down

How to Access Gmail When It’s Down - Gmail - Lifehacker
This is a great article with a number of tips on accessing Gmail through different methods.

Personally, I have Thunderbird set up on my laptop and an a POP3 account set up for it so I always have all my sent and received emails at hand if I loose my Internet connection. Also, as stated, when the Gmail interface went down the last time, the POP3 connection was still active, so I still had full Gmail access via Thunderbird.

Mozilla Thunderbird 2 Is Finally Ready

Thunderbird 2 is finally available. Download here. Install it on top of the old Thunderbird (1.5...).

Some of your old extensions and themes might not work (at first). The theme I was using did not work and things looked very messed up. I switched to the new default theme and things were fine. If you use small icons on the toolbars, you may need to Customize and uncheck and then re-check Use small icons to make this work.

Release notes are here if you are interested in all the details of what is new.

The only problem I had was with my Hotmail that I had set up with 2 extensions so I could read and send Hotmail email via Thunderbird. To fix it, I had to delete my Hotmail account within Thunderbird and recreate it using the new Webmail feature in Thunderbird. If you are dealing with this situation too, make sure to include "@hotmail.com" in the user name, and for the outgoing server, use the one you were using with the old Hotmail extension set up. The new account will default to an outgoing server of: "Webmail - localhost" which is a weird combination of your regular ISP account and hotmail and this does not work. Use the hotmail - local outgoing server that you set up previously - it works.
Then, I went onto my hotmail on the web and marked everything as UNread and then re-downloaded all the messages into Thunderbird. Adjust the account settings for the newly set up Hotmail in Thunderbird to keep messages on the server.

My Gmail, that I had set up as a POP account in Thunderbird still works fine.

If you want to force some old extensions to work in the new Thunderbird, install the Mr Tech Local Install extension (Firefox and Thunderbird) and then configure it to allow the old extensions to work (this doesn't work for the old webmail/hotmail extensions though). It may not work for some extensions.