Usability 
Mail2Web is a well established (the web version has been around since 1996) service with an excellent privacy policy that lets you retrieve POP3 or IMAP mail from any server using a Web or mobile Web interface.
There are several ways to use Mail2Web. If you just go to Mail2Web.com/pda/ you see a page where you enter your e-mail address and POP3 or IMAP password. The web application tries to determine your POP3 server name and login id from your e-mail address. If Intellilogin doesn't recognize your mail server you'll need to hit the "Advanced Login" link which brings up a form with fields for server name, account name, password, server type (IMAP or POP3) and whether to use SSL authentication or not. You get a custom URL (mail2web.com/pda/You_user_name) and when you load that URL you'll see a drop down listing all your e-mail servers and a password field. Mail2Web doesn't store your password which makes it more secure but also means that you have to login every time you launch Mail2Web.
The Mail2web PDA user interface is a quirky but works well once you get used to it. Mail2Web is a great service if you use e-mail servers that don't have a mobile front end but which support POP3 or IMAP, it's fast and even allows you to send e-mail with a reply to address that points back to your POP3 or IMAP server e-mail account.