Gmail Offline

Using Gmail but wish you could use it when not connected?  Take a look

Gmail offline: A guided tour | Webware - CNET

In short, people familiar with Gmail already are mostly familiar with its offline incarnation, which Google said it's releasing gradually to its users in coming days. The biggest difference is of course that you can't see new messages, and e-mails that you send are merely queued up until they can be delivered when a network connection is re-established