Getting your e-mail out of the cloud is often a good idea, whether it's to hedge against data loss or to meet archiving or indexing goals. Although a standard POP3/IMAP e-mail program (such as Mozilla Thunderbird) can connect to Gmail, if you just want backup and not a full-fledged mail program, some solutions are appearing. I recently reviewed Gmail Keeper, and now I look at a similar but ultimately less successful free program, Gmail Backup.
Gmail Backup is a standalone application. The interface is very straightfoward: Enter your account and password, select a backup directory, and go. It shows a scrolling list of messages downloaded as it works, so you know what it's doing. The data is stored in .eml format, which makes it easy to open in other programs. It will also bring down any file attachments--which is usually a benefit, but those who run this on netbooks with severely limited storage space might wish to be careful. (This is not a criticism of Gmail Backup, just a friendly warning.)
In terms of features and functionality, Gmail Backup is lacking compared to the $30 Gmail Keeper. It is lacks several features, such as profile management, scheduled backups, and filtering by labels. It also has no offline documentation. While this is becoming lamentably commonplace, Gmail Backup lacks even a Help button to open your browser to the documentation at Gmail-backup.com. To rub some salt in the wound, that documentation is extremely sparse and written in somewhat broken English. Further, according to Task Manager, Gmail Backup uses 18M of RAM when running, while Gmail Keeper uses a little less than 9M. (As a caveat, there are many different factors involved in system resource usage.)
After more than a year with no updates, in September 2010 the product (formerly a limited functionality trial with a commercial upgrade) was been repositioned as open source. No further work has been done, but this indicates that Gmail Backup is not completely dead, and it may be worth keeping an eye on it to see how it develops in the future.
At this point, there is very little to recommend Gmail Backup over Gmail Keeper, except this: Gmail Backup is free. If basic functionality is all you need, there's no sense in paying for features you won't use; Gmail Keeper's $30 price tag is well out of "impulse buy" range for a narrowly focused utility. Gmail Backup's open-source nature may be a valuable plus for some readers. If development does begin to pick up as promised, it may well add in more functionality over time.