I would love to be able to browse the web with the TV via Boxee. So my feature request would be an integrated web-browser optimized for none keyboard/mouse use (maybe similar like on the nintendo wii?).
I also agree with other people that live TV would add a lot to Boxees usability.
(if Boxee could act like a software satellite receiver would be amazing!)
Beeing able to control lights, heaters and having integrated Chats and VOIP similar like on LinuxMCE would be need but low priority in my point of view (at least for now )