I really like your web hosting plan. I want to sign up, but I wish web calendar and contact management is included. I think that would add value to your service since it would replace the need for a server like MS Exchange. I might go with another service because they have web calendar/contacts with their webmail.
SquirrelMail does include a calendar feature.
DreamHost offers WebDAV which allows me to incorporate my own calendar in an open format which can be read by a variety of applications. I’m not positive, but can the calendar & contacts info for Exchange only be read by MS Outlook on Windows?
The only application I’ve allowed myself to be dependent upon is Photoshop.
I use the Mozilla calendar addon myself, and use WebDAV to make my calendar file accessible both at home and at work (I use Mozilla in both places). I can also export the calendar in the format used by Mozilla onto my iPod, since the format is the same one used by Apple products.