Exactly. I use ownCloud for dropbox-like sync and sharing (it's better than dropbox!), postfix + dovecot + roundcube for email, a Jabber server for IM, and am

Exactly. I use ownCloud for dropbox-like sync and sharing (it's better than dropbox!), postfix + dovecot + roundcube for email, a Jabber server for IM, and am moving to Kolab for other groupware - Calendar, Tasks, RSS, Contacts, etc - encrypted on my linode instance. All connections are encrypted. And it's a VM image, so I can always take it out of their system and use it elsewhere.