Ability to import friends email addresses from your Hotmail, GMail, and Yahoo mail addressbook.
Should make it much easier for users to invite their friends to Boxee if this could be done directly from the Boxee GUI (or even from the boxee.tv website after login there)
Something to think about adding before the first Boxee final release
Open source code for PHP scripts is available to do this, see for example:
PS! I guess local Outlook Express, Outlook, Mac OS X Mail, and Thunderbird export and import into Boxee could be added as well for desktop uses that use a such e-mail client instead of webmail. One might even be able to extend this to import contacts from FaceBook, Myspace, and Orkut, all directly from Boxee and all to make it easier to invite friends without knowing their e-mail address by heart.