A feature I can only describe as Finder.
Basically, I want to be able to transfer files easily to and from the iPhone, preferably via any method of choosing (USB, Bluetooth, WiFi). Sometimes I need to type up something in just a text format on my MBP and then e-mail it through the iPhone. I don't want to pay $30 or whatever for some tethering feature that I would hardly use.
We just need the basic folders - documents, music, videos, pictures. Audio recordings could be stored in the music folder, potential video recordings in video. The others are self-explanatory.