This week I enabled Gmail Offline. You have to install Gears, which not seems like Google’s answer to Flash, Java, Silverlight, and the other mini-runtimes that need to leverage the client computer.
When I have a slow (or no) connection, I can flip Gmail into “Flaky Connection Mode”, and I can search my inbox, read, write, and send mail. When I have a connection again, Gmail syncs up just like normal. Very interesting feature. I wonder when I’ll have to start paying for Gmail. I’d be happy to.