For those of you who use Gmail/Hotmail and/or who want to archive and make searchable all their email locally there's a program that I've just come across called Mailstore at Mailstore.com. It's free for personal use and looks to be quite nifty. Runs on Windows only.

The best way to use Gmail is to turn on IMAP and install the account in a regular email client like Windows Live Mail on your machine.

This will allow you to access all your email without an internet connection, gives you a local backup, and hides the ads from view. All without any third party software. You can still use the web-based Gmail when travelling, at the office etc.

There are extensive instructions on the Gmail help pages explaining how to do it. Use IMAP, not POP3.

Mailstore actually supports a wide variety of email sources. From the website:

Internet mailboxes such as Gmail or Yahoo! Mail

Any POP3 and IMAP mailboxes

Microsoft Outlook 2000, XP, 2003, 2007, 2010

Microsoft Outlook Express and Windows Mail

Microsoft Exchange Server 2003, 2007, and 2010 mailboxes

Microsoft Office 365 (Exchange Online)

Hosted Exchange mailboxes

Mozilla Thunderbird and SeaMonkey

.EML and other email files